Interactive diabetes case 10: A 45-year-old patient with variable glucose values and hypoglycemia unawareness on insulin therapy – A2

ANSWER — Incorrect.

The patient calls in two weeks to report that she continues to have frequent episodes of hypoglycemia. The peak levels of hyperglycemia are not quite as high as in the past, possibly because she is not overtreating the hypoglycemic 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.

The patient has frequent hypoglycemia resulting from excessive daily doses of insulin. The patient also 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. While it would be helpful to know whether the patient has type 1 or type 2 diabetes, the changes in insulin management to address her current problems would probably be the same in either case. The patient needs a reduction in the total daily dose of insulin.

It is reasonable to reduce the NPH insulin dose at bedtime. However, a reduction of 4 units is not likely to have much of an effect. The patient has frequent episodes of hypoglycemia. She is on 44 units of NPH and 20 to 30 units of lispro a day. A reduction of 4 units of day is a small percentage of her total daily insulin dose. She needs a greater reduction in her insulin dose.

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