Endocrine Abstracts

Three phenotypes of prediabetes are known: impaired fasting glucose (IFG), Impaired glucose tolerance (IGT), and combined IFG/IGT. IFG is associated with impaired early phase and normal second-phase of insulin secretion. IGT is associated with both impaired early and late phase of insulin secretion. Numerous studies have demonstrated efficacy of lifestyle intervention in improving 2-hr oral glucose tolerance and fasting plasma glucose (FPG) in individuals with prediabetes, while other studies have failed to demonstrate improvements in 2-hr oral glucose tolerance and FPG. The aim of this study was to determine the influence of prediabetes phenotype on improvements in glucose homeostasis with resistance training (RT) or low-carb diet.

Methods: Obese prediabetics were treat by resistance training (RT) (IFG=22, IGT=24, IFG/IGT=20; or with low-carb diet (LC) (IFG=23, IGT=25, IFG/IGT=20). RT group (aged 45±5 years.; BMI 34±3.5 kg/m²) completed a resistance training twice per week (approximately 150 minutes per week) for 12 weeks without diet. Low-carb group (aged 44±3.9 years.; BMI 35±4.2 kg/m²) achieved low-carb diet for 12 weeks without physical activity. Body weight and waist circumference, fasting plasma glucose, 2-hr oral glucose tolerance, baseline assessments homeostasis model of insulin resistance (HOMA-IR), estimated insulin sensitivity index (ISI) and oral glucose-induced insulin were examined before and after the intervention.

Results: Waist circumference and BMI were decreased in both group with no difference between phenotypes. Fasting glucose did not change (P>0.05) in RT group but it improved in LC group (6.64±0.32 mmol/l vs 5.65±0.41 mmol/l, P<0.05). However, 2-hr oral glucose tolerance in RT group improved in those with IGT (9.34±0.52 mmol/l vs 7.31±0.71 mmol/l, P<0.05) and IFG/IGT (9.86±0.71 mmol/l vs 8.20±0.81 mmol/l). In LC group 2-hr oral glucose tolerance improved in those with IGT and IFG/IGT; FPG improved in those with IFG. There were no significant changes in ISI and HOMA-IR following the RT program but there were following LC program (P<0.05). Oral glucose-induced insulin secretion was reduced only in the LC group (65±11 mU/l vs 29±9.2 mU/l, P<0.05).

Conclusions: Resistance training appears to improve 2-hr oral glucose tolerance in individuals with prediabetes but did not improve FPG. Low-carb diet affect 2-hr oral glucose tolerance and FPG, and postprandial hyperinsulinemia in obese prediabetic individuals. The individualized approach is suggested to clinician’s for better treatment of individuals with prediabetes.