Caffeine Increases Ambulatory Glucose and Postprandial Responses in Coffee Drinkers With Type 2 Diabetes
- Duke University Medical Center, Durham, North Carolina
- Address correspondence and reprint requests to James D. Lane, PhD, Box 3830, Duke University Medical Center, Durham, NC 27710-0001. E-mail:
Recent laboratory studies demonstrated that caffeine exaggerates glucose and insulin responses to standardized carbohydrate loads in habitual coffee drinkers who have type 2 diabetes (1–3). Similar postprandial effects in everyday life could disrupt clinical efforts to maintain glucose control in patients with type 2 diabetes. The aim of this study was to examine the effects of a moderate dose of caffeine on glucose levels and postprandial glucose responses in free-living coffee drinkers with type 2 diabetes. We specifically predicted that caffeine administration would increase glucose concentrations during the day and exaggerate the glucose increases that followed meals when habitual coffee drinkers with type 2 diabetes were monitored during everyday life.
RESEARCH DESIGN AND METHODS—
The research protocol, approved by the Duke University Health Systems institutional review board, employed a double-blind crossover design to compare the effects of a moderate dose of caffeine (500 mg/day) with that of a placebo control. Subjects completed informed consent before testing and received $150.00 in compensation. The study group included 10 habitual coffee drinkers (five men and five women) who drank brewed coffee daily. All had at least a 6-month history of type 2 diabetes managed by a stable regimen of diet, exercise, and oral agents but no exogenous insulin. Subjects were free of major medical disorders, were …