Abstract
AIMS/INTRODUCTION: Diabetic polyneuropathy (DPN) is a factor that reduces lower extremity muscle strength (LEMS) in older type 2 diabetes patients. This relationship remains unclear in longitudinal studies. Therefore, we longitudinally investigated the apparent effects of DPN on changes in LEMS. Furthermore, we cross-sectionally examined relationships among DPN, LEMS, mobility and health-related quality of life. MATERIALS AND METHODS: Bodyweight-normalized (relative) knee extension force (KEF) was examined in 51 DPN and 54 non-DPN patients (68.9 ± 5.6 and 70.2 ± 5.9 years, respectively) at baseline and follow up at 3.6 ± 0.6 years. At follow up, mobility was measured using a 25-question geriatric locomotive function scale. Health-related quality of life was assessed using the five-dimensions of EuroQol for quality-adjusted life years calculation. RESULTS: Relative KEF in the DPN group was significantly lower at follow up (1.22 ± 0.47 Nm/kg) than at baseline (1.31 ± 0.47 Nm/kg; P < 0.05). DPN significantly affected changes in relative KEF. Mobility decreased by 41 and 65% in the non-DPN and DPN groups, respectively. Quality-adjusted life years were significantly lower in the DPN group (0.856 ± 0.131) than in the non-DPN group (0.920 ± 0.105; P < 0.01). Relative KEF was a significant independent variable that explained quality-adjusted life years. CONCLUSIONS: DPN clearly reduced LEMS in older type 2 diabetes patients within 4 years. Furthermore, DPN resulted in a loss of LEMS and decrease in mobility. Therefore, DPN development should be monitored closely, with glycemic control and LEMS kept at a high level to maintain health-related quality of life in older patients with type 2 diabetes.