MKSAP Quiz: hypoglycemia unawareness
This month's quiz asks readers to evaluate a 33-year-old woman with multiple recent episodes of severe hypoglycemia.
A 33-year-old woman is evaluated after having three episodes of severe hypoglycemia, each resulting in a visit to the emergency department, in the past month. Two of the episodes occurred while she was asleep, and the most recent one happened midafternoon yesterday. The patient has a 19-year history of type 1 diabetes mellitus and has been trying to lower her hemoglobin A1c level to less than 7.0% before she tries to get pregnant. She states that she no longer experiences any warning symptoms before she becomes hypoglycemic. The patient had an episode of diabetic ketoacidosis in her teens. She has mild background diabetic retinopathy, some numbness in her feet from peripheral neuropathy, and occasional orthostatic hypotension. She eats a healthy diet, counts carbohydrates, and adjusts her preprandial insulin intake. Medications are insulin glargine, 24 units at bedtime, and insulin glulisine, 6 to 10 units before breakfast, lunch, and dinner, depending on her planned carbohydrate intake and preprandial blood glucose level.
On physical examinations, vital signs are normal; BMI is 30.
Results of laboratory studies show a hemoglobin A1c value of 6.6% and no evidence of microalbuminuria.
Which of the following is the most appropriate treatment for this patient?
A. Increased carbohydrate intake at meals
B. Insulin dose reductions
C. α-Lipoic acid
D. Preprandial pramlintide
E. Substitution of insulin detemir for insulin glargine
MKSAP Answer and Critique
Correct answer: B. Insulin dose reductions.
The correct answer is B. Insulin dose reductions. This item is available to MKSAP 16 subscribers as item 19 in the Endocrinology section. Information about MKSAP 16 is available online.
This patient's dosages of both long-acting and rapid-acting insulin should be decreased by approximately 20%. Hypoglycemia is the major rate-limiting factor in attempting tight glycemic control, especially in patients with type 1 diabetes mellitus. For 48 to 72 hours after a severe episode of hypoglycemia, the body's ability to mount an adrenergic response is blunted, as is the strength of the counterregulatory response. This increases the likelihood of a second severe episode of hypoglycemia that will not be easily recognized (hypoglycemic unawareness), and thus a vicious cycle develops. The best treatment is to reduce the dosage of insulin and scrupulously monitor the blood glucose level for 1 week so that it does not become less than 100 mg/dL (5.6 mmol/L). This intervention allows the brain to reset its adrenergic responses.
Increasing her carbohydrate intake at meals is inappropriate because of her currently healthy diet, her anticipated pregnancy, and the potential for weight gain.
Although α-lipoic acid has shown some efficacy in management of painful diabetic neuropathy, it would have no effect on her hypoglycemic unawareness.
A preprandial injection of pramlintide, a synthetic long-acting analogue of the hormone amylin, is sometimes used in the management of type 1 diabetes to slow down stomach emptying, suppress glucagon secretion, and promote satiety. In this patient, however, pramlintide might actually increase the risk of hypoglycemia.
Switching from insulin glargine to insulin detemir without reducing the dose of insulin is unlikely to be helpful in stopping or reducing this patient's hypoglycemic episodes.
Key Point
- Hypoglycemia is the major rate-limiting factor in attempting tight glycemic control, especially in patients with type 1 diabetes mellitus.