Effect of a high vs low glycemic index Mediterranean Diet in adults at risk of type 2 diabetes: The MEDGICarb trial
Background:
Elevated postprandial glucose concentrations may contribute to development of impaired insulin secretion and impaired insulin sensitivity observed in the pathogenesis of type 2 diabetes. The glycemic index (GI) of carbohydrate-containing foods plays an important role in postprandial glucose concentrations. Consuming a healthy (HEP) Mediterranean-style diet (MED) is supported by extensive evidence of a reduced risk of the development of type 2 diabetes. Nevertheless, there have been no studies assessing the contribution of high- vs low-GI foods aiming to improve indices of glucose control and cardiometabolic health in the context of a MED-HEP.
The aim of the trial was to investigate the long-term effects of a low vs high GI on postprandial glycemia and glycemic variability in a MED-HEP context.
Method:
A multicenter, randomized, controlled dietary intervention trial, comparing high GI MED-HEP (GI value > 70) versus low GI MED-HEP (GI value < 55)-GI diets in adults at risk for type 2 diabetes. For 12 weeks, participants consumed a low-GI or high-GI MED-HEP. Assessment of postprandial plasma glucose and insulin responses (eight hours after breakfast and lunch), and daily glycemic variability via CGM were made at baseline and post-intervention. 160 adults (86 females, 74 males) with a waist circumference > 102 cm (male) or > 88 cm (females) and additional ≥ 2 metabolic syndrome traits, completed the intervention.
Result:
Postprandial insulin concentrations were higher after high-GI versus low-GI test meals at baseline (p</I> = 0.004), but not post-intervention (p</I> = 0.17). Postprandial glucose after high-GI test meal increased post-intervention, being greater compared to after low-GI test meal (*p </I>< 0.001). Average daily glucose concentrations decreased in both groups post-intervention. Indices of 24-h glycemic variability after the intervention were reduced in the low-GI group compared to baseline and the high-GI group.
Conclusion:
These findings suggest that low-GI foods may be an important part of a MED-HEP for postprandial and daily glucose control in people at risk for type 2 diabetes.
Keywords:
Glycemic index, Mediterranean diet, Type 2 diabetes, postprandial glucose
References:https://pubmed.ncbi.nlm.nih.gov/35277067/
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