Augmented Gastric Inhibitory Polypeptide and Insulin Responses to a Meal after an Increase in Carbohydrate (Sucrose) Intake

The gastric inhibitory polypeptide (GIP) response to certain stimuli may be exaggerated in patients with obesity and noninsulin-dependent diabetes mellitus. To explore the effects of increased caloric intake and dietary composition on GIP secretion, 20 normal lean volunteers underwent a 4- week ambulatory study. A baseline week (usual diet) was followed by 3 weeks in which the usual diet was supplemented with 45 g fat (diet A), 100 g carbohydrate in the form of sucrose (diet B), or 50 g protein (diet C) for 1 week each. Almost equal numbers of subjects followed sequence ABC, BCA, or CAB in this cross-over study. At the end of the baseline week and each study week, serum glucose, insulin, and GIP were measured in response to a 500-cal liquid test meal. Daily intake of carbohydrate, protein, or fat, as monitored by food records, increased significantly (P < 0.01) during the appropriate dietary periods, whereas body weight changed slightly, but not significantly, during the 3 study periods. No changes occurr...