Interactive diabetes case 10: A 45-year-old woman with variable glucose values and hypoglycemia unawareness on insulin therapy
- Lloyd Axelrod, MD
Lloyd Axelrod, MD
- Associate Professor of Medicine
- Harvard Medical School
You are asked to see a 45-year-old woman because of labile glucose control and recurrent hypoglycemia. At age 28 years, the patient had gestational diabetes treated with insulin. The baby weighed 8 lbs 6 oz at the time of delivery. Postpartum, the diabetes disappeared completely, only to return one year later. The patient was then treated with oral agents for a few months and then with insulin, which she has taken ever since. Her blood glucose values have always been variable. She had typical symptoms of hypoglycemia including tremulousness, palpitations, and diaphoresis until approximately five years ago. Now, she only rarely has any symptoms of hypoglycemia even when her blood glucose values are between 30 and 50 mg/dL (1.7 and 2.8 mmol/L). Sometimes family or coworkers notice inappropriate behavior and have her drink juice. She may have as much as two 8 ounce glasses of orange juice at a time, after which the blood glucose values rise to the 200 mg/dL (11.1 mmol/L) range. She tests her fingerstick blood glucose level four or five times a day. The glucose values in her diary for the last three months are as follows: before breakfast, 50 to 250 mg/dL, with most values below 100 mg/dL; two hours after breakfast, 48 to 349 mg/dL, with a few values below 100 mg/dL; before lunch, 32 to 303 mg/dL, with many values below 100 mg/dL; before supper, 53 to 285 mg/dL, with about 20 percent of the values below 100 mg/dL; two hours after supper, 136 to 232 mg/dL, with only five tests recorded; and at bedtime, 43 to 182 mg/dL, with only seven tests recorded. The patient has three meals a day, avoids sweets, and tries to keep her carbohydrate intake steady at each mealtime but does not count carbohydrates. Her glycated hemoglobin (A1C) values have been just above 6 percent. She takes NPH insulin 26 units before breakfast and 18 units at bedtime and uses lispro insulin before breakfast and supper (table 1).
She estimates that she uses 20 to 30 units of lispro insulin each day. She is on levothyroxine 150 micrograms a day for hypothyroidism with the thyroid-stimulating hormone (TSH) level within normal limits and lisinopril 20 mg a day for hypertension. Her father died at age 49 years of a heart attack, with diabetes diagnosed when he was in military service. Her mother had a goiter removed surgically. Her fraternal twin sister had diabetes with obesity; the diabetes disappeared after bariatric surgery. Her brother is living and well. The patient's weight is 164.5 pounds, height 5' 6", body mass index (BMI) 26.5 kg/m2.
What is your assessment and plan?
●You conclude that the patient has type 2 diabetes based on the history of gestational diabetes and the family history; that she has frequent hypoglycemia due to the use of the sliding scale; and that she needs basal insulin (NPH) only once a day. You order anti-thyroid peroxidase antibodies and anti-islet (glutamic acid decarboxylase [GAD] and islet antigen 2 [IA-2]) antibodies. You refer the patient to a dietitian to learn to count carbohydrates and limit orange juice to 4 ounces at any one time if possible but never more than 8 ounces, and advise a bedtime snack. You stop the sliding scale coverage. You stop the morning dose of NPH insulin and change the bedtime dose of NPH insulin to 35 units (approximately 80 percent of the current total NPH dose per 24 hours). (See "Interactive diabetes case 10: A 45-year-old woman with variable glucose values and hypoglycemia unawareness on insulin therapy - A1".)
●You conclude that the patient has type 1 diabetes based on the labile blood glucose values, the absence of obesity, the presence of hypothyroidism, and the family history of thyroid disease; that she has frequent hypoglycemia owing to excessive doses of basal insulin at bedtime, and that she needs less basal insulin at that time. You order anti-thyroid peroxidase antibodies and anti-islet (GAD and IA-2) antibodies. You refer the patient to a dietitian to learn to count carbohydrates and limit orange juice to 4 ounces at any one time if possible but never more than 8 ounces, and advise a bedtime snack. You reduce the bedtime dose of NPH insulin to 14 units. (See "Interactive diabetes case 10: A 45-year-old woman with variable glucose values and hypoglycemia unawareness on insulin therapy - A2".)