Effects of glucose-dependent insulinotropic polypeptide on gastric emptying, glycaemia and insulinaemia during critical illness: a prospective, double blind, randomised, crossover study (Critical Care)

IntroductionInsulin is used to treat hyperglycaemia in critically ill patients but can cause hypoglycaemia, which is associated with poorer outcomes. In health glucose-dependent insulinotropic polypeptide (GIP) is a potent glucose-lowering peptide that does not cause hypoglycaemia. The objectives of this study were to determine the effects of exogenous GIP infusion on blood glucose concentrations, glucose absorption, insulinaemia and gastric emptying in critically ill patients without known diabetes. Methods: A total of 20 ventilated patients (Median age 61 (range: 22 to 79) years, APACHE II 21.5 (17 to 26), BMI 28 (21 to 40) kg/m2) without known diabetes were studied on two consecutive days in a randomised, double blind, placebo controlled, cross-over fashion. Intravenous GIP (4pmol/kg/min) or placebo (0.9% saline) was infused between T?=??60 to 300?minutes. At T0, 100?ml of liquid nutrient (2?kcal/ml) containing 3-O-Methylglucose (3-OMG), 100mcg of Octanoic acid and 20?MBq Tc-99m Calcium Phytate, was administered via a nasogastric tube. Blood glucose and serum 3-OMG (an index of glucose absorption) concentrations were measured. Gastric emptying, insulin and glucagon levels and plasma GIP concentrations were also measured. Results: While administration of GIP increased plasma GIP concentrations three- to four-fold (T?=??60 23.9 (16.5 to 36.7) versus T?=?0 84.2 (65.3 to 111.1); P