OBJECTIVETo evaluate whether fat quality, in the context of meals with high-(HGI) or lowglycemic index (LGI), influences postprandial blood glucose (PPG) response in patients with type 1 diabetes.
RESEARCH DESIGN AND METHODSAccording to a randomized crossover design, 13 patients with type 1 diabetes on insulin pump consumed two series (HGI or LGI) of meals with the same carbohydrate quantity while differing for amount and quality of fat: 1) low in fat ("low fat"), 2) high in saturated fat (butter), or 3) high in monounsaturated fat (extra-virgin olive oil) (EVOO). Premeal insulin doses were based on insulinto-glycemic load ratios. Continuous glucose monitoring was performed and 6-h PPG evaluated.
RESULTSPPG was significantly different between HGI and LGI meals (P = 0.005 for time 3 glycemic index interaction by repeated-measures analysis [RMA]), being significantly higher during the first 3 h after the HGI meals with a later tendency to an opposite pattern. In the context of HGI meals, PPG was significantly lower after EVOO than after low fat or butter (P < 0.0001 for time 3 meal interaction by RMA), with a marked difference in the 0-to 3-h glucose incremental area under the curve between EVOO (mean 6 SD 198 6 274 mmol/L 3 180 min) and either low fat (416 6 329) or butter (398 6 355) (P < 0.05). No significant differences were observed in PPG between the three LGI meals.
CONCLUSIONSCarbohydrate quality of a mixed meal influences shape and extent of PPG. Besides, using EVOO in a HGI meal attenuates the early postprandial glucose response observed when this meal is consumed with either low fat or butter. Therefore, an optimal prandial insulin administration would require considering, in addition to the quantity of carbohydrates, the quality of both carbohydrate and fat.
The aim of the study was to evaluate the effects of a supervised physical training added to a healthy diet-rich in either carbohydrate and fibre (CHO/fibre) or monounsaturated fatty acids (MUFA)-on postprandial dyslipidaemia, an independent cardiovascular risk factor particularly relevant in type 2 diabetes (T2D). Participants were forty-five overweight/obese subjects with T2D, of both genders, in good blood glucose control with diet or diet+metformin, with normal fasting plasma lipids. According to a parallel groups 2 × 2 factorial design, participants were randomized to an 8-week isoenergetic intervention with a CHO/fibre or a MUFA diet, with or without a supervised low-volume aerobic training programme. The main outcome of the study was the incremental area under the curve (iAUC) of lipid concentrations in the plasma chylomicron+VLDL lipoprotein fraction, isolated by preparative ultracentrifugation (NCT01025856). Body weight remained stable during the trial in all groups. Physical fitness slightly improved with training (VO2 peak, 16 ± 4 vs. 15 ± 3 ml/kg/min, M ± SD, p < 0.05). Postprandial triglyceride and cholesterol iAUCs in plasma and chylomicron+VLDL fraction decreased after the CHO/fibre diet, but increased after the MUFA diet with a significant effect for diet by two-way ANOVA (p < 0.05). The addition of exercise training to either dietary intervention did not significantly influence postprandial lipid response. A diet rich in carbohydrates and fibre reduced postprandial triglyceride-rich lipoproteins compared with a diet rich in MUFA in patients with T2D. A supervised low-volume physical training did not significantly influence these dietary effects.
Calculating prandial insulin bolus based on glycaemic load counting is feasible in a real-life setting and may improve postprandial glucose control in people with T1D.
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