Polypeptide Worsens Postprandial Hyperglycemia in Type 2 Diabetes

(GIP), unlike glucagon-like peptide (GLP)-1, lacks glucose-low-ering properties in patients with type 2 diabetes. We designed this study to elucidate the underlying pathophysiology. RESEARCH DESIGN AND METHODS—Twenty-two insulin-naïve subjects with type 2 diabetes were given either synthetic human GIP (20 ng kg1 min1) or placebo (normal saline) over 180 min, starting with the first bite of a mixed meal (plus 1 g of acetaminophen) on two separate occasions. Frequent blood samples were obtained over 6 h to determine plasma GIP, GLP-1, glucose, insulin, glucagon, resistin, and acetaminophen levels. RESULTS—Compared with placebo, GIP induced an early post-prandial increase in insulin levels. Intriguingly, GIP also induced an early postprandial augmentation in glucagon, a significant elevation in late postprandial glucose, and a decrease in late postprandial GLP-1 levels. Resistin and acetaminophen level