Interactive diabetes case 10: A 45-year-old patient with variable glucose values and hypoglycemia unawareness on insulin therapy – A3

ANSWER — Correct.

The patient returns in six weeks. The occurrence of low blood glucose values has been markedly reduced since the initial visit but not eliminated. She is drinking less orange juice for low glucose readings or symptoms, and high glucose values are less frequent and less elevated. She has lost 6 pounds as a result of an improved diet and less orange juice. Her glucose diary indicates the following: fasting glucose values are alternately below 60 and over 200 mg/dL; the values before lunch vary from 34 mg/dL to the high 200s; the values before supper vary from 39 mg/dL to the mid 200s; the values at bedtime are usually in the 100 to 200 mg/dL range. You reduce the dose of NPH insulin before breakfast to 18 units.

The patient has hypoglycemia unawareness, a consequence of frequent episodes of hypoglycemia, in which patients lose the autonomic (adrenergic and cholinergic) early warning symptoms of hypoglycemia and have symptoms of neuroglycopenia as the first indication of hypoglycemia.

Five months after the initial visit, the patient has lost a total of 10.5 pounds. She has learned to count carbohydrates. Hypoglycemia unawareness appears to have resolved. However, the glucose values remain variable. The glucose diary reveals the following: the fasting values are in the 80s to high 100s; the values before lunch vary from the 70s to the high 100s, with occasional values below 50 mg/dL; values at supper and at bedtime are in the 100 to 200 mg/dL range, with occasional low values.

The anti-islet (glutamic acid decarboxylase [GAD] and islet antigen 2 [IA-2]) antibody tests are negative. These tests are approximately 80 percent sensitive and 99 percent specific for type 1 diabetes at the time of diagnosis. In addition, the percentage of patients who are antibody positive decreases with increasing duration of type 1 diabetes. These results do not exclude the possibility of type 1 diabetes and are consistent with (not diagnostic of) type 2 diabetes. The anti-thyroid peroxidase antibody test is strongly positive.

What is your assessment and plan?

●You conclude that the sliding scale should be reduced to prevent the hypoglycemic episodes, especially at the higher end of the scale. You change the sliding scale (table 1). (See "Interactive diabetes case 10: A 45-year-old patient with variable glucose values and hypoglycemia unawareness on insulin therapy – B1".)

●You advise her to stop using the insulin sliding scale. In its place, you advise her to take a prandial (nutritional) dose of lispro and to use correction doses for glucose values above 120 mg/dL (6.7 mmol/L). By the rule of 1500, you recommend 1 unit of lispro for each 12 grams of carbohydrate and 1 unit for every 40 mg/dL (2.2 mmol/L) of blood glucose above 120 mg/dL (6.7 mmol/L), estimating a total daily insulin dose of approximately 40 units at this time (see "Interactive diabetes case 3: Hypoglycemia in a patient with type 1 diabetes"), for an approach to estimating the dose of short- and very short-acting insulins. (See "Interactive diabetes case 10: A 45-year-old patient with variable glucose values and hypoglycemia unawareness on insulin therapy – B2".)