Gastrointestinal effects of extra-virgin olive oil associated with lower postprandial glycemia in type 1 diabetes

Summary Objective To explore the possible mechanisms behind the lower glycemic response observed when extra-virgin olive oil (EVOO) is added to a high-glycemic index meal in patients with type 1 diabetes (T1D). Research design and methods According to a randomized cross-over design, eleven T1D patients (6 women, 5 men) on insulin pump consumed in the metabolic ward, one week apart, three high-glycemic index meals differing only for amount and quality of fat: high-monounsaturated fat (EVOO), high-saturated fat (Butter), and low-fat (LF). Before and after the meals, blood glucose (continuous glucose monitoring), gastric emptying rate (ultrasound technique), and plasma concentrations of glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide GIP (ELISA), glucagon (RIA), and lipids (colorimetric assays) were evaluated. Results Blood glucose iAUC (mmol/lx360 min) was lower after the EVOO (690 ± 431) than after the Butter (1320 ± 600) and LF meals (1007 ± 990) (M ± SD, p = 0.041 by repeated measures ANOVA). Gastric antrum volume was significantly larger in the early (60–90 min) postprandial phase (106 ± 21 vs. 90 ± 16 ml, p = 0.048) and significantly smaller in the late phase (330–360 min) (46 ± 10 vs. 57 ± 22 ml, p = 0.045) after the EVOO than after Butter meal. EVOO significantly increased postprandial GLP-1 iAUC (261 ± 311) compared to Butter (189 ± 349) (pmol/Lx180 min, p = 0.009). Postprandial GIP and glucagon responses were not significantly different between EVOO and Butter. Postprandial triglyceride iAUC was significantly higher after EVOO (100 ± 53) than after Butter (65 ± 60) (mmol/l × 360 min, p = 0.048). Conclusions Changes in gastric emptying and GLP-1 secretion and reduced glucose absorption through glucose-lipid competition may contribute to lower glycemia after a high-glycemic index meal with EVOO in T1D patients. Clinical trials number NCT02330939.