Effects of dietary quality, physical activity and weight loss on glucose homeostasis in persons with and without prediabetes in the PREMIER trial

Abstract

AbstractAimsWe examined the contribution of changes in diet quality, physical activity and weight loss to improvements in insulin resistance (HOMA‐IR index) and fasting glucose concentrations in a long‐term behavioural trial. Furthermore, we compared the effects of lifestyle changes on glycaemic markers for individuals with and without prediabetes.Materials and methodsThe PREMIER trial was an 18‐month parallel randomized trial of the impact of behavioural lifestyle interventions implementing lifestyle recommendations (dietary changes, physical activity, moderate weight loss) in adults with prehypertension or stage 1 hypertension. We analysed data on 685 men and women without diabetes. Data on body weight, fitness (treadmill test), dietary intake (24‐h recalls) and glycaemic outcomes were collected at baseline and at 6 and 18 months. We used general linear models to assess the association between the exposure variables and glycaemic markers.ResultsThe mean (SD) age was 49.9 (8.8) years, the mean (SD) body mass index was 32.9 (5.7) kg/m2, and 35% had prediabetes at baseline. Weight loss and improvements in fitness and diet quality were each significantly associated with lower HOMA‐IR and fasting glucose concentrations at 6 and 18 months. Mediation analysis indicated that the effects of fitness and diet quality were partly mediated by weight loss, but significant direct effects of diet and fitness (independent of weight changes) were also observed. Furthermore, insulin sensitivity and fasting glucose improved significantly in participants with and without prediabetes.ConclusionsOur findings indicate that behavioural lifestyle interventions can substantially improve glucose metabolism in persons with and without prediabetes and that the effects of diet quality and physical activity are partly independent of weight loss.