Loss of lower extremity muscle strength based on diabetic polyneuropathy in older patients with type 2 diabetes: Multicenter Survey of the Isometric Lower Extremity Strength in Type 2 Diabetes: Phase 2 study

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.