Interactive diabetes case 10: A 45-year-old patient with variable glucose values and hypoglycemia unawareness on insulin therapy – A1

ANSWER — Incorrect.

Several days after the start of the new insulin regimen, the patient has a seizure at 3:30 AM. Her husband calls 911. The emergency medical technicians find a fingerstick blood glucose value of 33 mg/dL (1.9 mmol/L), give her dextrose 50 percent in water (D50W) intravenously, and transport her to the nearest emergency department, where the clinical and neurologic evaluations are unremarkable.

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 diabetes 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. Because she frequently has low fasting blood glucose values, it would be unwise to increase the bedtime dose of NPH insulin.

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