Impact of medium and long chain triglycerides consumption on appetite and food intake in overweight men

BACKGROUND: Medium chain triglycerides (MCT) enhance thermogenesis and may reduce food intake relative to long chain triglycerides (LCT). The goal of this study was to establish the effects of MCT on appetite and food intake and determine whether differences were due to differences in hormone concentrations. METHODS: Two randomized, crossover studies were conducted in which overweight men consumed 20 g of MCT or corn oil (LCT) at breakfast. Blood samples were obtained over 3 h. In Study 1 (n=10), an ad lib lunch was served after 3 h. In Study 2 (n=7), a pre-load containing 10 g of test oil was given at 3 h and lunch was served 1 h later. Linear mixed model analyses were performed to determine the effects of MCT and LCT oil on change in hormones and metabolites from fasting, adjusting for body weight. Correlations were computed between differences in hormones just before the test meals and differences in intakes after the two oils for Study 1 only. RESULTS: Food intake at the lunch test meal after the MCT pre-load (Study 2) was (mean ± SEM) 532 ± 389 kcal vs. 804 ± 486 kcal after LCT (P < 0.05). MCT consumption resulted in a lower rise in triglycerides (P = 0.014) and glucose (P = 0.066) and a higher rise in peptide YY (P = 0.017) and leptin (P = 0.036) compared to LCT (combined data). Correlations between differences in hormone levels (GLP-1, PYY) and differences in food intake were in the opposite direction to expectations. CONCLUSIONS: MCT consumption reduced food intake acutely but this does not seem to be mediated by changes in GLP-1, PYY, and insulin

Secretion of glucagon-like peptide-1 in patients with type 2 diabetes mellitus:systematic review and meta-analyses of clinical studies

AIMS/HYPOTHESIS: We carried out a systematic review of clinical studies investigating glucagon-like peptide-1 (GLP-1) secretion in patients with type 2 diabetes and non-diabetic controls and performed meta-analyses of plasma total GLP-1 concentrations during an OGTT and/or meal test. METHODS: Random effects models for the primary meta-analysis and random effects meta-regression, subgroup and regression analyses were applied. RESULTS: Random effects meta-analysis of GLP-1 responses in 22 trials during 29 different stimulation tests showed that patients with type 2 diabetes (n=275) and controls without type 2 diabetes (n=279) exhibited similar responses of total GLP-1 (p=NS) as evaluated from peak plasma concentrations (weighted mean difference [95% CI] 1.09 pmol/l [−2.50, 4.67]), total AUC (tAUC) (159 pmol/l×min [−270, 589]), time-corrected tAUC (tAUC min(−1)) (0.99 pmol/l [−1.28, 3.27]), incremental AUC (iAUC) (−122 pmol/l×min [−410, 165]) and time-corrected iAUC (iAUC min(−1)) (−0.49 pmol/l [−2.16, 1.17]). Fixed effects meta-analysis revealed higher peak plasma GLP-1 concentrations in patients with type 2 diabetes. Subgroup analysis showed increased responses after a liquid mixed meal test (peak, tAUC and tAUC min(−1)) and after a 50 g OGTT (AUC and tAUC min(−1)), and reduced responses after a solid mixed meal test (tAUC min(−1)) among patients with type 2 diabetes. Meta-regression analyses showed that HbA(1c) and fasting plasma glucose predicted the outcomes iAUC and iAUC min(−1), respectively. CONCLUSIONS/INTERPRETATION: The present analysis suggests that patients with type 2 diabetes, in general, do not exhibit reduced GLP-1 secretion in response to an OGTT or meal test, and that deteriorating glycaemic control may be associated with reduced GLP-1 secretion