Table 53-10

Basal-Bolus (Physiological) Insulin Therapy: Indications and Precautions

Patient Selection Criteria

Type 1 diabetes, otherwise healthy patients (>7 years of age) who are highly motivated, engaged in diabetes selfmanagement and are able to adhere to a complex insulin regimen. Must be willing to test blood glucose

concentrations multiple times daily and inject four doses of insulin daily, on average

Women with diabetes who plan to conceive

Pregnant patients with diabetes (preexisting)

Patients poorly controlled on conventional therapy, 2–3 injections daily (includes type 2 diabetes patients)

Technical ability to test blood glucose concentrations

Intellectual ability to interpret blood glucose concentrations and adjust insulin doses appropriately

Access to trained and skilled medicalstaff to direct treatment program and provide close supervision

Avoid or Use Cautiously in Patients Who Are Predisposed to Severe Hypoglycemic Reactions or in

Whom Such Reactions Could Be Fatal

Patients with counter-regulatory insufficiency

β-Adrenergic blocker therapy

Autonomic insufficiency

Adrenal or pituitary insufficiency

Patients with coronary or cerebral vascular disease

(Note: Counter-regulatory hormones released in response to hypoglycemia may have adverse effects in these

individuals.)

Unreliable, nonadherent individuals, including those who abuse alcohol or drugs and those with psychiatric

disorders

Insulin pumps are particularly useful in patients with frequent, unpredictable

hypoglycemia, or marked dawn phenomena (see Case 53-3). Others have described

the methods by which insulin doses are established and altered in patients using the

insulin pump.

91,99 Because A.H. has just been diagnosed, she should be initiated on a

basal-bolus SC insulin therapy. Once she has acquired these skills, she may be

considered for pump therapy.

Clinical Use of Insulin

INITIATING INSULIN THERAPY

CASE 53-2, QUESTION 6: How should multiple daily insulin injections be initiated in A.H.?

A conservative TDD of insulin is estimated empirically or according to guidelines

similar to those listed in Table 53-9 in newly diagnosed patients and will differ in

patients with Type 1 and Type 2 diabetes. Many weight-based empiric dose

calculations have been proposed as listed in Table 53-9 for patients with both Type

1 and Type 2 diabetes; however, these regimens are mostly beneficial for patients

with Type 1 diabetes because these patients are completely insulin deficient. For

patients with Type 2 diabetes, initial basal insulin doses that are weight-based or a

starting dose of ~10 units daily are appropriate options based on patient-specific

information. Insulin doses would then be adjusted based on HBG levels.

100

For a basal-bolus insulin regimen, insulin glargine, insulin detemir, or insulin

degludec could be used as the basal insulin with bolus doses of a rapid- or shortacting insulin (insulin lispro, insulin aspart, insulin glulisine) given at mealtime.

During the initial visit, A.H. needs to learn how to inject her insulin (see Case 53-2,

Question 8), how to test her BG (Table 53-11), how and when to test for ketones

(either urine or blood), and how to recognize and treat hypoglycemia (Table 53-12).

She also needs to understand the importance of meal planning and the relationship

between carbohydrate intake and insulin action (Table 53-13). It is very important

not to overwhelmA.H. with information on the first visit. One should be particularly

sensitive to the psychological impact of this diagnosis on A.H., address her major

1.

2.

3.

4.

5.

6.

7.

8.

concerns, and provide only the information that is absolutely essential before the next

visit. Between visits, she should be assessed and provided information on an asneeded basis by phone. Table 53-14 lists important areas of patient education.

A reasonable first approach for A.H. is to provide a TDD of 24 units of insulin

(~0.5 units/kg). Because 50% of the daily dose should be given as basal insulin with

the remainder given as rapid-acting insulin divided into three doses, A.H. would take

the following: 12 units of insulin glargine once daily (morning or bedtime) with 4

units of insulin aspart or lispro given approximately 5 to 10 minutes before each

meal.

71,100Alternatively, if insulin detemir is used, the dose would generally be split

twice daily (6 units BID) as the duration of action of insulin detemir is typically less

than 24 hours when given at such a small dose. Caveat: As A.H.’s glucose

concentration returns to normal, glucose toxicity will recede and she may require less

insulin.

SELECTING AN INSULIN DELIVERY DEVICE

CASE 53-2, QUESTION 7: What kind of insulin delivery device should be prescribed for A.H.?

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Table 53-11

Self-Monitored Blood Glucose Testing: Areas of Patient Education

When and How Often To Test

Technique

How and when to calibrate the glucose monitor

Review all “buttons” and their purposes. Identify battery type. Review cleaning procedures, if applicable

Preparation

Calibrate monitor/set code for batch of test strips, if required

Insert test strip to turn machine on (some meters require user to turn machine on)

Prepare all materials: tissue, strip, and lancet

Remember to close the lid of the strip container immediately. Strips exposed to air and moisture deteriorate

rapidly

Wash hands with warm water. Dry thoroughly. A wet finger causes blood to spread rather than form a

drop. Milk the finger from the base to ensure an adequate flow of blood

Lance the tip of the finger. Avoid the pads of the finger where nerve endings are concentrated

Hold the finger below the heart with the lanced area pointing toward the floor

Once a sufficient amount of blood is available, quickly apply blood to designated area of the test strip.

Depending on the strip type, the blood sample is placed in an area on the surface of the strip or it is applied

to the side of the strip where it is taken up by capillary action

Record Results in a Log Book and Bring to All Clinician Visits. Include relevant information

regarding diet or exercise

How To Use Results To Achieve Glycemic Targets; Educate Patients on What To Do With Their

Blood Glucose Readings (e.g., adjust their insulin dose; modify their carbohydrate content)

Table 53-12

Hypoglycemia

Definition

Blood glucose concentration <60 mg/dL: Patient may or may not be symptomatic

Blood glucose <40 mg/dL: Patient is generally symptomatic

Blood glucose <20 mg/dL: Can be associated with seizures and coma

Signs and Symptoms

Blurred vision, sweaty palms, generalized sweating, tremulousness, hunger, confusion, anxiety, circumoral

tingling, and numbness. Patients vary with regard to their symptoms. Behavior can be confused with alcohol

inebriation. Patients become combative and use poor judgment

Nocturnal hypoglycemia: nightmares, restless sleep, profuse sweating, morning headache, morning “hangover.”

Not all patients have symptoms during nocturnal hypoglycemia

Clinical Considerations

Irregular eating patterns

↑ Physical exercise

Gastroparesis (delayed gastric emptying)

Defective counter-regulatory responses

Excessive dose of insulin or insulin secretagogues (sulfonylureas, glinides)

Alcohol ingestion

Drugs

Treatment

Ingest 10–20 g of rapidly absorbed carbohydrate. Repeat in 15–20 minutes if glucose concentration remains less

than 60 mg/dL or if patient is symptomatic. Follow with complex carbohydrate/protein snack if mealtime is not

imminent

The following are examples of food sources that provide 15 g of carbohydrate:

Orange, grapefruit, or apple juice; regular, nondiet soda 1/2 cup

Fat-free milk 1 cup

Grape juice, cranberry juice cocktail 1/3 cup

Sugar 1 tbsp or 3 cubes

Lifesavers 5–6 pieces

Glucose tablets 3–4 tablets

If patient is unconscious, the following measures should be initiated:

Glucagon 1 mg SC, IM, or IV (generally administered IM in outpatient setting; mean response time, 6.5 minutes)

Glucose 25 g IV (dextrose 50%, 50 mL; mean response time, 4 minutes)

IM, intramuscular; IV, intravenous; SC, subcutaneous.

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Table 53-13

Interpreting Self-Monitored Blood Glucose Concentrations

Test Time Target Insulin Dose Target Meal/Snack

Prebreakfast

(fasting)

Predinner/bedtime intermediate-acting or basal insulin Dinner or bedtime snack

Prelunch Prebreakfast regular or rapid-acting insulin Breakfast or mid-morning snack

Predinner Prebreakfast intermediate-acting insulin or prelunch

regular or rapid-acting insulin

Lunch or mid-afternoon snack

Bedtime Predinner regular or rapid-acting insulin Dinner

2-hour postprandial Premeal regular or rapid-acting insulin Preceding meal or snack

2–3 AM or later Predinner intermediate-acting insulin or basal insulin if

given in AM

Dinner or bedtime snack

Considerations: (a) Assumes a regular meal pattern. For patients who travel, have odd working or sleeping hours,

or have irregular meal patterns, these guidelines may not apply. (b) Assumes administration of regular insulin 30 to

60 minutes before meals or rapid-acting insulin 0 to 15 minutes before meals and a normal pattern of insulin

response (see Table 53-8 for factors that can alter insulin absorption and response). (c) If prebreakfast

concentrations are high, rule out reactive hyperglycemia (Somogyi reaction or posthypoglycemic hyperglycemia).

Consider contribution of dawn phenomenon as well. Whenever blood glucose concentrations are high, consider

reactive hyperglycemia (excessive insulin doses). (d) Consider accuracy of reported test results: (i) Do they

correlate with the glycosylated hemoglobin (A1C) and patient’s signs and symptoms? (ii) What is the patient’s

medication adherence? Could results be fabricated? (iii) Is the patient’s technique appropriate? Check timing,

adequate blood sample, machine, strips, and calibration (Table 53-11). (iv) Are insulin kinetics altered? (v) What is

the carbohydrate content, quality, and regularity of meals?

Table 53-14

Areas of Patient Education

Diabetes: Pathogenesis and the complications

Hyperglycemia: Signs and symptoms

Ketoacidosis: Signs and symptoms (Tables 53-22 and 53-23)

Hypoglycemia: Signs, symptoms, and appropriate treatment (Table 53-12)

Exercise: Effect on blood glucose concentrations and insulin dose (Table 53-19)

Diet: See text. Emphasis placed on carbohydrate counting because the carbohydrate is responsible for 90% of

the rise in blood glucose after a meal

Insulins:

Injection technique

Types of insulin

Time action profiles (onset, peak, and duration)

Storage

Stability (look for crystallization and precipitation with NPH insulin)

Therapeutic goals: A1C, fasting, preprandial, and postprandial blood glucose levels, cholesterol, triglyceride, blood

pressure (refer to Lipid Chapter 8 and Essential Hypertension Chapter 11)

SMBG testing: Table 53-13

Interpretation of SMBG testing results

Foot care: Inspect feet daily; wear well-fitted shoes; avoid self-care of ingrown toenails, corns, or athlete’s foot;

see a podiatrist

Sick day management: Table 53-20

Cardiovascular risk factors: Tobacco use, high blood pressure, obesity, elevated cholesterol

Importance of annual ophthalmologic examinations; tests for microalbuminuria; keeping up-to-date with

immunizations

A1C, glycosylated hemoglobin; NPH, neutral protamine Hagedorn; SMBG, self-monitored blood glucose.

Insulin delivery is achieved utilizing syringes, prefilled insulin delivery devices

(pens), or through oral inhalation. Insulin syringes are plastic, disposable syringes

with needles that are extremely fine (typically 30–31 gauge), sharp, and well

lubricated to ease insertion. Pen needles and syringes have been improved so that

insulin injections are relatively painless if proper technique is used. The lengths of

needles are 15/64-inch (6-mm) 5/16-inch (8-mm), or ½-inch (12.7 mm).

100 Research

has shown that there is no medical reason why a patient would require use of a

needle longer than 4 to 6 mm for insulin administration as skin thickness does not

vary between different demographics. Previous thoughts that larger or obese patents

require longer needle length for proper insulin administration have been disproven.

Manufacturers produce 1-, 0.5-, and 0.3-mL syringes for U-100 insulin. For patients

such as A.H., using fewer than 30 units of insulin per injection, the 0.3-mL syringe is

preferred for ease of reading the dose markings on the syringe. Insulin syringes are

available in 1-unit increments or 0.5-unit increments. One-half-unit increments are

useful for pediatric patients and for patients who count carbohydrates, because

mealtime insulin doses can be rounded to the 0.5 unit.

101

Insulin pen devices are also available for injecting insulin. Pen devices are often

preferred because they make insulin administration much easier, especially for

patients who need to take their insulin doses away from home. They also can increase

dosing accuracy. The pens are particularly useful for patients with (a) regimens

consisting of multiple daily doses of rapid- or short-acting insulin before meals and

snacks (such as A.H.), (b) a fear of needles, (c) impaired visual or dexterity

problems, (d) hectic work schedules or lifestyle, or (e) a need to train alternative

individuals who administer insulin (e.g., school nurses, siblings). Additionally,

studies have shown that use of insulin pen devices vs. vial and syringe insulin

administration may result in fewer discontinuations of insulin therapy and improve

overall adherence to an insulin regimen.

102,103

Pens eliminate the need to withdraw insulin, and the insulin dose is dialed up on

the device. Pen devices are available as a disposable prefilled pen or a durable pen

in which an insulin cartridge is replaced. Most typically used are the prefilled pens

which contain a built-in, single-use insulin cartridge. U-100 formulations contain 300

units of insulin, whereas concentrated insulins will contain more units in each device.

Pen devices are available to dose insulin in 1-unit (most) and 0.5-unit increments

(HumaPen

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Luxura HD). Pen needles are available in 30-, 31-, and 32-gauge needles and

5/32-inch, (4-mm), 3/16-inch (5-mm), 1/4-inch (6-mm), or 5/16-inch (8-mm) lengths,

but there is no medical rationale to use needles longer than 6 mm. Patients are

advised to use a new disposable needle for each injection. Unfortunately, limited

health insurance coverage and higher copays may deter pen use. A detailed review of

pen devices (both insulin and noninsulin) was published in 2014.

104

For insulin delivery using an insulin pump, see Case 53-2, Questions 3 and 5.

If she elected to use a syringe, a 0.3-mL U-100 insulin syringe with a short needle

length should be prescribed for A.H. Subjectively, patients can “feel” the difference

between different brands, or they may prefer the “ease of bubble removal,” physical

characteristics, or packaging of one syringe over another. If she elected to use an

insulin pen, a prefilled pen for insulin glargine and insulin aspart or insulin lispro are

available. The shortest possible needle length (4 mm for pen needles and 6 mm for

syringes) should be prescribed for A.H.

MEASURING AND INJECTING INSULIN

CASE 53-2, QUESTION 8: How should A.H. be instructed to administer her insulin injections?

Injection

A.H. should prepare an area for injection. Alcohol swabs may be used to clean the

rubber stopper of the insulin vial (or pen device). To inject the insulin SC, A.H.

should be instructed to firmly pinch up the area to be injected (this creates a firm

surface for the injection) and to quickly insert the needle perpendicularly (90-degree

angle) into the center of this area. Note however that if pinching is only necessary

then AH is using a syringe that is 6 mm or greater.

101 The syringe should be held

toward the middle or back of the barrel, like a pencil. Anxious patients have a

tendency to “choke” the hub of the syringe, and this prevents proper needle insertion.

A 45-degree angle of injection may be used for infants and very thin individuals who

have little SC fat, especially in the thigh area.

101 The site should not be massaged,

because this may accelerate the absorption and onset of action of insulin (Table 53-

8). When using an insulin pen, the needle should be embedded within the skin for

about 5 to 10 seconds after depressing the dosing knob to ensure full delivery of the

insulin dose.

101

Rotating Injection Sites

The primary sites used for injecting insulin are the lateral thigh, abdomen (avoid 2-

inch radius around the navel), and upper arm (Fig. 53-5). The ADA recommends that

insulin injections be rotated within the same anatomic region to decrease chances of

variability in insulin absorption.

101,105 Many practitioners recommend using the

abdominal area because absorption from this site is least affected by exercise and is

the most predictable. Alternatively, A.H. can be instructed to rotate her morning

injection within one region (e.g., the abdomen) and her evening injection in another

anatomic region. This minimizes the variables that can alter her response to insulin.

Rotating injection sites also were recommended at one time to avoid the

lipodystrophic effect of insulin (lipohypertrophy and lipoatrophy); however, because

insulin has been purified, these complications are less common and the importance of

rotation is less critical. Nevertheless, repetitive use of the same site of injection may

still result in lipohypertrophy, and it does toughen the skin, making needle penetration

more difficult. Furthermore, insulin absorption from lipohypertrophic sites can be

slowed.

101

Figure 53-5 Selecting insulin injection sites. A: Areas of the body most suitable for insulin injections. The actual

point of injection should be varied each time within a chosen body area. Give injections at least one inch apart.

Patients should consult with their provider or diabetes educator about which area is most appropriate for use. B:

The site where insulin should be injected. Insulin is injected in the subcutaneous tissue (between the skin and the

muscle layer). If the skin is pinched up and the needle is pushed all the way in, the need will reach the proper

space under the skin. (A, LifeART image © 2011. Lippincott Williams & Wilkins. All rights reserved; B, Adapted

from Springhouse. Lippincott’s Visual Encyclopedia of Clinical Skills. Philadelphia: Wolters Kluwer Health; 2009,

with permission.)

Agitation

A.H. does not need to agitate insulin glargine or aspart because these are clear

insulins. For NPH insulin, which is a suspension, or a combination/mixed insulin, the

vial or pen must be gently agitated before use. The vial should be rolled between the

palms of the hands to minimize foaming. A pen device is inverted back and forth to

mix the insulin. Agitation is only required for insulin suspensions (i.e., insulin

mixtures).

Measurement

First, A.H. should make sure her hands and the injection site are clean. She should

withdraw the plunger to the level of insulin she intends to inject (e.g., 12 units for her

insulin glargine dose), then she should insert the needle into the vial and inject the air

to prevent creation of a vacuum within the vial. The vial then should be inverted with

the syringe inserted, and 12 units of insulin glargine should be withdrawn. The bevel

of the needle should

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be well below the surface of the insulin to avoid withdrawing air or bubbles into the

syringe. Insulin glargine must not be mixed in the same syringe with her rapid-acting

insulin, and it should be injected into a different site if it is injected at the same time

as her glargine dose.

101

The barrel of the syringe should be held at eye level to check for air bubbles and

to allow accurate placement of the plunger tip at the 12-unit mark. If bubbles are

present, they should be removed by tapping the syringe gently to coax the bubbles to

the top of the barrel, where they can be injected back into the insulin vial. To remove

air bubbles in an insulin pen, prime the pen with 2 units of insulin before each use

(repeat until insulin drop appears at tip of pen needle). Also, remove and discard the

pen needle from the device in between uses to prevent air bubbles from

accumulating.

SELF-MONITORING OF BLOOD GLUCOSE

CASE 53-2, QUESTION 9: How should A.H. be educated to self-monitor her BG? What types of selfmonitoring BG tests are available, and what are the major differences among them? How accurate are results

obtained from home BG testing? Should she begin CGM at the same time?

The ADA recommends that most individuals with diabetes should attempt to attain

and achieve normoglycemia as safely as possible. SMBG is a tool to allow patients

to safely achieve these goals. For patients with Type 1 diabetes, this can be achieved

by the routine use of SMBG. SMBG is also important in (a) pregnancy complicated

by diabetes, (b) patients with unstable diabetes, (c) patients with a propensity to

severe ketosis or hypoglycemia, (d) patients prone to hypoglycemia who may not

experience the usual warning symptoms, and (e) patients using an insulin pump. The

technology in this area is changing rapidly, with new monitors with advanced

features being introduced yearly.

90

All monitors use test strips and are self-timing, requiring no patient action after the

blood is placed on the strip. Several factors should be taken into account when

evaluating a monitor and its appropriateness for an individual. The primary

considerations are ease of use, accuracy relative to a reference standard, reliability,

insurance coverage, and cost.

90 Most monitors no longer require coding for the test

strips, which simplifies the process for patients. Convenience factors include meter

size, volume of blood required for testing, site to obtain sample (e.g., finger versus

alternative site such as forearm), capacity of the meter to store BG values (memory)

and data such as comments, required testing time, ability to download BG values,

general availability of strips, ability to turn off audible signals, audible readings and

instructions for visually impaired, and availability of technical support. Some

devices are less reliable for use in anemic patients (e.g., renal transplant patients),

and all function most reliably within certain temperature ranges (usually 60°F–95°F)

and humidity (generally <90%) conditions. Strips are sensitive to light, moisture, and

temperature extremes and must be stored and handled with care.

Patient education regarding any testing procedures, the importance of logging

results in a diary, and test times are critical. Ultimately, A.H. should be taught how

and when to check her BG levels in order to optimize her insulin regimen (Table 53-

15).

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Table 53-15

Guidelines for Dosing Insulin

Basic Insulin Doses

First, adjust the basic insulin dose (i.e., the dose that the patient will be instructed to take daily)

Only adjust insulin doses if a pattern of response is observed under stable diet and exercise circumstances. That

is, the same response to insulin is observed for ≥3 days, particularly for the basal insulin dose. It is important to

verify the stability of diet and exercise. Consider adjusting these variables as well

Unless all levels are >200 mg/dL, try to adjust one component of insulin therapy at a time

Start with the insulin component affecting the FBG concentration. This glucose level often is the most difficult to

control and often affects all other glucose concentrations measured throughout the day. The basal insulin dose is

often what is adjusted to control the FBG. However, if the dinner insulin dose (of rapid-acting or short-acting

insulin) is not adequate, this can result in hyperglycemia that can persist into the morning. The basal dose is

typically adjusted by 2–4 units, no sooner than every 3–4 days

Prandial/mealtime insulin dose:

For patients eating a set amount of carbohydrate at meals: typically adjust the basic insulin dose by 1–2 units at

a time. The amount given is based on the individual patient’s response to insulin. This can be determined by

looking at the patient’s total daily dose (TDD) using the “500 rule” (see the following, and Table 53-9)

For patients using the insulin-to-carbohydrate method (i.e., 1 unit rapid-acting or short-acting insulin for every x

g of carbohydrate), adjust the “ratio” based in the patient’s response to insulin (e.g., 1:8, 1:10, 1:12, 1:15, 1:18,

1:20)

General Principles

Assumes that diet and physical activity are stable. Set a reasonable goal initially. This may mean the upper limits

of the acceptable concentrations may be high initially (e.g., <200 mg/dL). Move toward a more ideal goalslowly.

Supplementary Insulin Doses (with rapid-acting or short-acting insulin)

Once the basic dose of prandial insulin has been established, supplemental doses of rapid- or short-acting insulin

can be prescribed to correct preprandial hyperglycemia. For example, if the goal is 140 mg/dL and the glucose

value is 190 mg/dL, administer one additional unit. Supplemental doses also can be used when the patient is ill

(Table 53-15)

Algorithms for correction doses are based on the patient’s sensitivity to insulin using the “1,500 or 1,700 rule”

(Table 53-9)

If premeal glucose concentrations are <60–70 mg/dL, the dose of aspart, glulisine, lispro, or regular insulin

administered before the meal is ↓ by 1–2 units; insulin administration is delayed until just before the meal; the

mealshould include an extra 15 g of glucose if the value is <50 mg/dL

If supplemental doses before a given meal are required for ≥3 days, the basic insulin dose should be adjusted

appropriately. For example, if a patient taking lispro before meals requires an extra 2 units before lunch for ≥3

days, 2 units should be added to the prebreakfast dose, or the insulin-to-carbohydrate ratio at breakfast should be

adjusted (e.g., if patient was using a 1:15 ratio, a 1:12 ratio could be used). Rapid-acting insulin doses should be

adjusted no more frequently than every 2–3 days

Anticipatory Insulin Doses (with rapid-acting or short-acting insulin)

The basic insulin dose is ↑ or ↓ based on the anticipated effects of diet or physical activity

↑ Aspart/glulisine/lispro or regular insulin by 1 unit for each additional 15 g of carbohydrate ingested (e.g., holiday

meal) or ↓ the usual dose by 1–2 units if the meal is smaller than usual (Table 53-9)

See Table 53-19 for recommended insulin adjustments for exercise

FBG, fasting blood glucose.

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Used properly, available monitors provide reasonably accurate results that can be

used by patients to manage their diabetes. Problems with a monitor can be detected

by performing a quality-control test once weekly and with each new vial of strips.

Table 53-16 lists factors that can affect results of SMBG test results. Any time

SMBG values are inconsistent with the patient’s symptoms or A1C values, sources of

error should be evaluated. A.H.’s technique should be reviewed periodically,

because clinical decisions are often based on the patient’s BG testing record.

Because A.H. is just starting insulin therapy and SMBG, it would be reasonable to

hold off on considering CGM until she becomes comfortable with these skills. Then,

she and her practitioner could assess whether CGM would be useful.

TESTING FREQUENCY

CASE 53-2, QUESTION 10: How often should A.H. test her BG concentrations?

Although the exact frequency and timing of BG tests should be dictated by

individualized patient goals, most patients with Type 1 diabetes using basal-bolus

insulin regimens should perform SMBG at least 3 times daily or more according to

the ADA.

38 Glucose monitoring should also be performed more frequently if needed,

such as when therapy is modified, prior to exercise, when the patient suspects

hypoglycemia, after treatment of hypoglycemia, or when the patient is performing a

critical task such as driving. Because A.H. is being initiated on insulin therapy with

the goal of normoglycemia, she should ideally self-monitor her BG 4 times/day

(before meals and at bedtime) for 2 weeks until the pattern of blood sugar fluctuation

can be assessed and adjustments can be made. Motivated patients may continue this

degree of monitoring, but it may be reduced to twice daily for patients on long-term

insulin. Varying the time of day in which testing is performed will allow the clinician

and patient to make informed decisions on how to make adjustments. For those

patients who are not using an intensive insulin regimen, such as patients with Type 2

diabetes using insulin, there is insufficient evidence as to how often a patient should

check their BG due to the decreased risk of hypoglycemia. Instead patients along with

their providers should determine the appropriate frequency and timing to check BG

levels in order to best optimize drug therapy and decrease risk for hypoglycemia.

106

The objective of ongoing, frequent BG testing is to determine whether

normoglycemia is being achieved, assess effectiveness of drug therapy as well as the

impact of meals, food, illness, or exercise on BG levels. Typical times to check BG

may include: before meals and snacks, 2 hours postprandial, at bedtime and

occasionally at 2 to 3 AM. However, it can be challenging for patients to adhere to

such a rigorous regimen. A.H. should set her alarm for 3 AM 2 or 3 times/week and

test her BG. BG concentrations measured before meals allow patients and clinicians

to determine whether the rapid-acting insulin dose is appropriate for the amount of

carbohydrate consumed; FPG levels are used to determine whether the basal insulin

dose is adequate; and the 2 to 3 AM BG level is used to identify nocturnal

hypoglycemia. For example, the BG measured before dinner reflects the action of

A.H.’s prelunch aspart dose on food she has eaten for lunch, as well as hepatic

glucose production between meals. Increasingly, patients who use carbohydrate

counting with rapid-acting insulins test 2-hour postprandial levels when initiating

therapy to enhance proper dosage adjustment (Table 53-13).

Table 53-16

Factors that Can Alter Self-Monitored Blood Glucose Test Results:

Troubleshooting

Glucose monitor not coded for batch of test strips

a

An inadequate amount of blood applied to test strip

b

Improper storage of test strips (temperature and humidity)

a

Dirty glucose monitor

a

Low battery

a

Test performed outside of altitude, temperature, and humidity operating conditions

a

Low

c or high

b hematocrit

Dehydration

b

Hyperosmolar, nonketotic state

b

Lipemia

a

Interfering substances

Nonglucose sugars (e.g., maltose, xylose, galactose) in meters using GDH-PQQ test strips

115

Large amounts of acetaminophen

c

Large amounts of ascorbic acid or salicylates (rare)

b

aEffect unpredictable

bValues tend to be lower

cValues tend to be higher

GDH-PQQ, glucose dehydrogenase pyrroloquinolinequinone.

Source: Heinemann L. Quality of glucose measurement with blood glucose meters at the point-of-care: relevance

of interfering factors. Diabetes Technol Ther. 2010;12:847.

The importance of frequent BG testing in patients newly diagnosed with Type 1

diabetes cannot be overemphasized. When BG is tested less frequently than 4 times

daily, it becomes difficult to adjust insulin doses based on infrequent readings or to

assess

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patterns in glucose levels (i.e., pattern management). If patients refuse to test 4

times daily, they should be encouraged to test 4 times daily on representative days of

the week or to test at different times of the day each day so that a weekly profile can

be developed. A.H. also should be encouraged to test her BG concentration any time

she is feeling unusual, if she is experiencing hypoglycemic symptoms, or to evaluate

the effect of unusual circumstances on her BG concentration (e.g., increased physical

exercise, a large holiday meal, final examinations, a family crisis).

38

USING BLOOD GLUCOSE TEST RESULTS TO EVALUATE INSULIN

DOSES

CASE 53-2, QUESTION 11: A.H. was instructed to inject herself with 12 units of insulin glargine each

evening and to give 4 units of insulin aspart just before each meal. She was asked to test her BG 4 times daily

(before meals and at bedtime), to record her results and other unusual events or symptoms during the day, and

to bring her BG logbook to the clinic. A.H. was also instructed to track her food and record the number of

carbohydrates she ingested at each meal. The initial goal of therapy is to lower her to eliminate symptoms of

hyperglycemia. The ultimate goal is to achieve fasting glucoses of 80 to 130 mg/dL and postprandial values of

less than 180 mg/dL. One week later, trends in her BG concentrations were as follows:

Time Glucose Concentration (mg/dL)

7 AM 160–200

Noon 220–260

5 PM 130–180

11 PM 140–180

Occasional 3 AM tests averaged 160 mg/dL, and A.H.’s urine is negative for ketones. She eats

approximately four carbohydrate servings for breakfast (60 g) and two to four carbohydrate servings for lunch

and dinner (30–60 g). Subjectively, A.H. feels a bit better, and her weight has stabilized, but she still urinates 2

to 3 times nightly. How would you interpret these results, and how should A.H.’s insulin doses be altered?

Values from SMBG appropriately form the basis for insulin adjustments.

Ultimately, the goal is to move motivated patients toward being able to recognize

their own glucose trends and make insulin adjustments accordingly based on

recommendations between the patient and provider.

56 Before using A.H.’s BG results

to adjust her insulin dose, it is important to observe and reassess her testing

technique. One also should determine whether there were any unusual circumstances

in her life such as acute illness, diet changes, drug therapy changes, or exercise

patterns during the past week that may have affected her response to insulin. Once

these have been ruled out as confounding factors, one can begin making adjustments

in A.H.’s insulin dose, realizing that fine-tuning will be impossible until a consistent

diet and exercise pattern have been instituted.

Several principles must be kept in mind whenever BG tests are used to adjust a

patient’s basic insulin dose (Table 53-17). Because many factors can alter a patient’s

response to insulin, it is important to review BG concentration trends measured for a

minimum of 3 days to adjust the basic insulin dose (i.e., the dose the patient will use

every day). The only exception to this rule is the use of supplemental insulin doses to

correct exceptionally high glucose concentrations after A.H. has acquired

sophisticated insulin adjustment skills (see Case 53-2, Question 16). SMBG results

should always be evaluated in conjunction with A1C values.

The daily dose of insulin glargine is inadequately controlling A.H.’s FPG and

should be increased by 2 to 4 units. A more conservative approach would be to

increase the dose to 14 units each evening (or a designated time of day that she will

be able to do consistently) and further titrate as needed.

92 She is achieving some

response from her lunchtime dose of insulin aspart, but there is room for

improvement in her meal insulin coverage overall. The BG concentration of 160

mg/dL at 3 AM indicates that rebound hyperglycemia is an unlikely cause of her high

fasting levels (see Case 53-2, Question 13, and Case 53-3). As an initial step toward

control, A.H.’s daily dose of insulin glargine should be increased in an attempt to

control her fasting hyperglycemia. However, this approach does not address A.H.’s

elevated prelunch values. Her intake of carbohydrates also varies from meal to meal.

Thus, a more appropriate method would be to calculate the insulin-to-carbohydrate

ratio for A.H. and allow her to determine her premeal aspart dose based on the

amounts of carbohydrates she will ingest at each meal. A typical starting point for the

insulin-to-carbohydrate ratio is 1 unit to every 15 g of carbohydrate ingested. To

calculate her insulin-to-carbohydrate ratio, the “500 rule” is used: Divide the number

500 by her TDD of

p. 1098

p. 1099