Response of blood glucose and GLP-1 to different food temperature in normal subject and patients with type 2 diabetes

BACKGROUND: Eating behavior is a major factor in type 2 diabetes. We investigated the different responses of glucose-regulating hormones to cold and hot glucose solutions in normal subjects and patients with type 2 diabetes. METHODS: In this crossover, self-controlled study, normal subjects (N=19) and patients with type 2 diabetes (N=22) were randomly assigned to a hot (50 °C) or a cold (8 °C) oral glucose-tolerance test (OGTT) and switched to the other temperature the subsequent day. Blood glucose, insulin, GIP, GLP-1, and cortisol were measured at 0, 5, 10, 30, 60, and 120 min during each OGTT. After the hot OGTT, all subjects ingested hot (>42 °C) food and water for that day; after the cold OGTT, they ingested food and water at room temperature (≤24 °C). Continuous glucose monitoring (CGM) was performed throughout. RESULTS: Compared to cold OGTT, blood glucose was significantly higher with hot OGTT in both groups (both P<0.05). Insulin and GLP-1 levels were significantly higher with hot OGTT in normal subjects only (both P<0.05). GIP and cortisol responses did not differ by temperature in either group. CGM showed that normal subjects had significantly higher 24-h mean glucose (MBG) (6.11±0.13 vs 5.84±0.11 mmol/L, P=0.021) and higher SDBG (0.59±0.06 vs 0.48±0.05 mmol/L, P=0.043) with hot meals; patients with T2DM had higher MBG only (8.88±0.39 vs 8.46±0.38 mmol/L, P=0.022). CONCLUSIONS: Food temperature is an important factor in glucose absorption and GLP-1 response; these temperature-elicited differences are diminished in type 2 diabetes.