Robinson Lindsay E, Savani Sonali, Battram Danielle S, McLaren Drew H, Sathasivam Premila, Graham Terry E
Department of Human Biology and Nutritional Sciences, University of Guelph, Guelph, ON, Canada.
J Nutr. 2004 Oct;134(10):2528-33. doi: 10.1093/jn/134.10.2528.
Caffeine ingestion negatively affects insulin sensitivity during an oral glucose tolerance test (OGTT) in lean and obese men, but this has not been studied in individuals with type 2 diabetes. We examined the effects of caffeine ingestion on insulin and glucose homeostasis in obese men with type 2 diabetes. Men (n = 12) with type 2 diabetes (age = 49 +/- 2 y, BMI = 32 +/- 1 kg/m(2)) underwent 2 trials, 1 wk apart, in a randomized, double-blind design. Each trial was conducted after withdrawal from caffeine, alcohol, exercise, and oral hypoglycemic agents for 48 h and an overnight fast. Subjects randomly ingested caffeine (5 mg/kg body weight) or placebo capsules and 1 h later began a 3 h 75 g OGTT. Caffeine increased (P < 0.05) serum insulin, proinsulin, and C-peptide concentrations during the OGTT relative to placebo. Insulin area under the curve was 25% greater (P < 0.05) after caffeine than after placebo ingestion. Despite this, blood glucose concentration was also increased (P < 0.01) in the caffeine trial. After caffeine ingestion, blood glucose remained elevated (P < 0.01) at 3 h postglucose load (8.9 +/- 0.7 mmol/L) compared with baseline (6.7 +/- 0.4 mmol/L). The insulin sensitivity index was lower (14%, P = 0.02) after caffeine than after placebo ingestion. Overall, despite elevated and prolonged proinsulin, C-peptide, and insulin responses after caffeine ingestion, blood glucose was also increased, suggesting an acute caffeine-induced impairment in blood glucose management in men with type 2 diabetes.
在口服葡萄糖耐量试验（OGTT）期间，摄入咖啡因会对瘦人和肥胖男性的胰岛素敏感性产生负面影响，但尚未在2型糖尿病患者中进行过此类研究。我们研究了摄入咖啡因对肥胖2型糖尿病男性胰岛素和葡萄糖稳态的影响。12名2型糖尿病男性（年龄=49±2岁，体重指数=32±1kg/m²）以随机、双盲设计进行了两项试验，间隔1周。每项试验均在停用咖啡因、酒精、运动和口服降糖药48小时并禁食过夜后进行。受试者随机摄入咖啡因（5mg/kg体重）或安慰剂胶囊，1小时后开始进行3小时的75g OGTT。与安慰剂相比，咖啡因使OGTT期间的血清胰岛素、胰岛素原和C肽浓度升高（P<0.05）。摄入咖啡因后胰岛素曲线下面积比摄入安慰剂后大25%（P<0.05）。尽管如此，咖啡因试验中的血糖浓度也升高了（P<0.01）。摄入咖啡因后，葡萄糖负荷后3小时的血糖（8.9±0.7mmol/L）与基线（6.7±0.4mmol/L）相比仍保持升高（P<0.01）。摄入咖啡因后的胰岛素敏感性指数比摄入安慰剂后低14%（P=0.02）。总体而言，尽管摄入咖啡因后胰岛素原、C肽和胰岛素反应升高且持续时间延长，但血糖也升高了，这表明咖啡因会急性损害2型糖尿病男性的血糖管理。
