Exercise-Related Hypoglycemia in Type 2 Diabetes Treated With Oral Glucose-Lowering Medications

摘要

D.L. is a 58-year-old African-American man and business executive who wasdiagnosed with type 2 diabetes at the age of 52 years. In addition todiabetes, he has a history of hypertension and coronary artery disease (CAD).The diagnosis of CAD was made in late 2005, after D.L. experienced an episodeof chest pressure and shortness of breath while at work.He consulted his primary care physician, who referred him for acardiovascular evaluation to assess probable myocardial ischemia. Theevaluation included a graded exercise test with thallium nuclear imaging,which revealed ischemic changes with exercise and reduced exercise tolerance.Coronary arteriography showed occlusion of the left anterior descending branchof the coronary artery (LAD), and angioplasty of the LAD with stent placementwas performed. D.L. was referred to cardiac rehabilitation for an exercise andlifestyle change program.D.L. had completed 2 months of supervised exercise when he returned to hisprimary care physician after experiencing hypoglycemia both during and afterexercise. Before this time, progression of his physical activity program hadbeen excellent. He was exercising three mornings per week from 7:30 to 8:30A.M. in the rehabilitation program and was walking 30-45 minutes on weekenddays. Hypoglycemia was now a safety concern for both D.L. and the cardiacrehabilitation staff and was a barrier to further progression of his exerciseprogram.On examination, D.L.'s height was 6 feet, 2 inches, and his weight was 215lb (BMI 27.6 kg/m2). He had lost 15 lb in 2.5 months byconsistently exercising and following a reduced-fat, calorie-controlled mealplan. His medications included glyburide, 7.5 mg with breakfast and 5 mg withdinner, plus metformin, 1,000 mg twice daily with breakfast and dinner. He wastaking enalapril, 10 mg twice daily, and aspirin, 325 mg daily. His bloodpressure was 118/76 mmHg and had been well controlled when measured pre- andpost-exercise.D.L.'s blood glucose record revealed that, in the past 2 weeks, four valueswere < 70 mg/dl, indicating hypoglycemia, and three additional values werebelow his target range of 80-140 mg/dl but not low enough to indicatehypoglycemia. Two episodes of hypoglycemia occurred during and two occurred≥ 1 hour after exercise. His blood glucose meter showed a 14-day glucoseaverage of 118 mg/dl.Because continued weight loss was a goal, D.L. and his physician consideredthe additional food and calories that he was consuming to treat hypoglycemia.D.L. initially treated hypoglycemia by drinking 6 oz of orange juice. However,each episode occurred at least 2 hours before his next planned meal.Therefore, he followed this treatment with an additionalcarbohydrate-containing snack. D.L.'s physician estimated that D.L. wasconsuming a minimum of 200 unplanned calories with each episode ofhypoglycemia.Based on these findings, the physician modified D.L.'s medication plan bydiscontinuing glyburide and initiating glimepiride (a sulfonylurea associatedwith lower risk ofhypoglycemia1), 4 mgeach morning. D.L. was to continue his metformin dosage at 1,000 mg twicedaily. He was also advised to monitor his blood glucose before, during, andafter each exercise session in addition to continuing routine monitoring andto call the office in 1 week with his blood glucose readings.One week later, D.L. reported that he was feeling better overall whenexercising and was again making progress in cardiac rehabilitation. His bloodglucose values were within his target range during and after exercise with theexception of three values that were between 70 and 80 mg/dl. D.L.'s physicianadvised him to reduce his glimepiride dose to 3 mg each morning, to continuemonitoring frequently with exercise, and to again follow up by phone in 1week. At this time, D.L. reported that all blood glucose values during andafter exercise were within his target range.