Diets with a low glycaemic load have favourable effects on prediabetes progression and regression: a prospective cohort study.

BACKGROUND: To date, no study assessing the associations among glycaemic index (GI), glycaemic load (GL) and progression to diabetes has focused specifically on prediabetes. Moreover, the available data on the association between these variables and regression to normal glucose regulation (NGR) are insufficient. Therefore, the present study aimed to evaluate the longitudinal associations among GI, GL and prediabetes outcomes.

METHODS: This prospective study included 640 adults aged 40-79 years with prediabetes at baseline. Dietary data were assessed using a previously validated 3-day food record. The participants were divided into three groups according to GI and GL tertiles. Outcomes were defined based on annual oral glucose tolerance test results.

RESULTS: During a median of 5 years of follow-up, 127 incident cases of diabetes and 249 incident cases of NGR were identified. Dietary GL was positively associated with the risk of developing diabetes and negatively associated with the likelihood of reaching NGR at least once. Comparing the highest and lowest tertiles of GL, the multivariable-adjusted hazard ratios (95% confidence intervals) were 1.85 (1.07-3.21) for progression and 0.65 (0.44-0.96) for regression. No association was observed between GI and prediabetes outcomes in the fully adjusted models.

CONCLUSIONS: Among patients with prediabetes, high dietary GL was positively associated with diabetes risk. Furthermore, a low-GL diet contributed to an increased incidence of reaching NGR.