Mitochondrial dysfunction in the elderly: possible role in insulin resistance

Abstract

Insulin resistance is a major factor in the pathogenesis of type 2 diabetes in the elderly. To investigate how insulin resistance arises, we studied healthy, lean, elderly and young participants matched for lean body mass and fat mass. Elderly study participants were markedly insulin-resistant as compared with young controls, and this resistance was attributable to reduced insulin-stimulated muscle glucose metabolism. These changes were associated with increased fat accumulation in muscle and liver tissue assessed by 1H nuclear magnetic resonance (NMR) spectroscopy, and with a approximately 40% reduction in mitochondrial oxidative and phosphorylation activity, as assessed by in vivo 13C/31P NMR spectroscopy. These data support the hypothesis that an age-associated decline in mitochondrial function contributes to insulin resistance in the elderly.

Fig. 1

Plasma concentrations of glucose, insulin, and fatty acids before and after an oral glucose tolerance test (24) in young and elderly participants. (A) Glucose [P = 0.10 for the area under the curve (AUC) for the elderly (16,978 ± 656) as compared with the controls (14,495 ± 1,116)]. (B) Insulin [asterisks indicate P < 0.03 for AUC for the elderly (6590 ± 853) as compared with the controls (3986 ± 519)]. (C) Fatty acids (P = 0.08 for the basal concentration of fatty acids in the elderly versus the controls).