Effects of intragastric administration of L-leucine and L-isoleucine on gastric emptying, gut hormone release and blood glucose in normal weight, overweight or obese type 2 diabetic patients.

Assessment of blood glucose and gastric emptying, following administration of control, or 10g L-Leucine, or 10g L-Isoleucine 30 min prior to a standardised mixed nutrient drink. Subjects will receive, in randomized, double-blind fashion: i) an intragastric bolus infusion of 10g L-Leucine (100ml); ii) an intragastric bolus infusion of 10g L-Isoleucine (100ml); iii) an intragastric bolus infusion of saline (control) (100ml). Subjects will receive one infusion per visit. All bolus infusion will be administered by the primary researcher. Study visits will be separated by 3-7 days. In addition, during study visits, the primary researcher will be present in order to closely monitor adherence to study protocol. For each study visit a baseline blood sample, VAS, and breath sample will be collected (t = -31). At t = -31 the infusion will be administered over 1 minute using a feeding tube. At t = -20, -10, and -1 min further blood samples will be collected and VAS completed. At t = -1 min, subjects will consume, within 1 minute, a mixed-nutrient drink (Resource Plus, 500 kcal, 325 ml) labeled with 100 mg of 13C-acetate for measurement of gastric emptying by breath sampling, and 3g 3-OMG for measurement of glucose absorption. Blood samples and VAS will be taken every 15 minutes, and breath samples will be taken every 5 min, over the next hour (t = 0 to 60 min). Over the following hour, VAS and blood samples will be collected every half hour (t = 90, 120), and breath samples collected every 15 min (t = 75, 90, 105, 120).