Abstract
PurposeTo determine if prediabetes phenotype influences improvements in glucose homeostasis with resistance training (RT).MethodsOlder, overweight individuals with prediabetes (n = 159; aged 60±5 yrs; BMI 33±4 kg/m2) completed a supervised RT program twice per week for 12 weeks. Body weight and composition, strength, fasting plasma glucose, 2-hr oral glucose tolerance, and Matsuda-Defronza estimated insulin sensitivity index (ISI) were assessed before and after the intervention. Participants were categorized according to their baseline prediabetes phenotype as impaired fasting glucose only (IFG) (n = 73), impaired glucose tolerance only (IGT) (n = 21), or combined IFG and IGT (IFG/IGT) (n = 65).ResultsChest press and leg press strength increased 27% and 18%, respectively, following the 12-week RT program (both p<0.05). Waist circumference (-1.0%; pre 109.3±10.3 cm, post 108.2±10.6 cm) and body fat (-0.6%; pre 43.7±6.8%, post 43.1±6.8%) declined, and lean body mass (+1.3%; pre 52.0±10.4 kg, post 52.7±10.7 kg) increased following the intervention. Fasting glucose concentrations did not change (p>0.05) following the intervention. However, 2-hr oral glucose tolerance improved in those with IGT (pre 8.94±0.72 mmol/l, post 7.83±1.11 mmol/l, p<0.05) and IFG/IGT (pre 9.66±1.11mmol/l, post 8.60±2.00 mmol/l) but not in those with IFG (pre 6.27±1.28mmol/l, post 6.33± 1.55 mmol/l). There were no significant changes in ISI or glucose area under the curve following the RT program.ConclusionsRT without dietary intervention improves 2-hr oral glucose tolerance in individuals with prediabetes. However, the improvements in glucose homeostasis with RT appear limited to those with IGT or combined IFG and IGT.Trial RegistrationClinicalTrials.gov: NCT01112709
Highlights
There were no significant changes in insulin sensitivity index (ISI) or glucose area under the curve following the resistance training (RT) program
14.3% of Americans are estimated to suffer from type 2 diabetes mellitus (T2D) and 38.0% are estimated to suffer from prediabetes [1]
Because 90% of glucose disposal occurs in skeletal muscle, these findings suggest that the skeletal muscle is insulin resistant in impaired glucose tolerance only (IGT), but normal or near normal in impaired fasting glucose only (IFG) [4]
Summary
14.3% of Americans are estimated to suffer from type 2 diabetes mellitus (T2D) and 38.0% are estimated to suffer from prediabetes [1]. Individuals with prediabetes are at high risk with up to 70% eventually progressing to T2D over their lifetimes [2]. Not all individuals with prediabetes progress at the same rate. Impaired fasting glucose and IGT are associated with impaired glucose-stimulated insulin secretion, the pattern of β-cell dysfunction in each case is distinct [4]. Impaired glucose tolerance is associated with both impaired early and late phase insulin secretion [5]. IFG is associated with normal or near-normal insulin-stimulated whole-body glucose disposal [4,6]. Because 90% of glucose disposal occurs in skeletal muscle, these findings suggest that the skeletal muscle is insulin resistant in IGT, but normal or near normal in IFG [4]. IFG is associated with more severe hepatic insulin resistance than IGT [7]
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