The association between muscle indicators and bone mass density and related risk factors in the diabetic elderly population: Bushehr Elderly Health (BEH) Program

Background: Loss of muscle mass and strength and bone mass density are complications of the aging process. Studies show that the prevalence of sarcopenia and osteoporosis may be higher in patients with diabetes. Therefore, this study was aimed to investigate the relationship between muscle mass and strength indices and bone mass density in diabetic elderly.

Materials and methods: This cross-sectional study was conducted based on the data collected during the Bushehr Elderly Health (BEH) Program, stage II. Diabetes was defined as FPG ≥ 126 mg/dl or HbA1C ≥ 6.5 or taking anti-diabetic medication. Dual x-ray absorptiometry (DXA, Discovery WI, Hologic Inc, USA) was used to measure bone mineral density, fat mass, trabecular bone score (TBS) and muscle mass. Muscle strength was measured by grip strength.Osteoporosis was defined as the bone mineral density of ≥ 2.5 standard deviations (SD) below the average value of young normal adults (T-score of ≤ -2.5 SD) in the femoral neck, or lumbar spine (L1-L4) or total hip. To determine the relationship between skeletal muscle index (SMI) and muscle strength on bone status in a continuous scale was used from linear regression. To estimate the effect of SMI and muscle strength on osteoporosis was used from modified Poisson regression for analysis.

Results: This study included 759 diabetic elderly with a mean age of 68.6 years and 56.9% of them were women. Skeletal muscle index (SMI) was related to all sites of BMDs and TBS L1-L4 after adjusted in full models (P-value < 0.001). The largest coefficients were observed for BMD L1-L4 in all models (β: 0.043 g/cm²; 95% CI: 0.030-0.057 in full model). Muscle strength was also associated with BMDs and TBS. Only, in model 2 (adjustments for age and sex effect), there was no significant relationship between muscle strength and BMD L1-L4 and TBS L1-L4. The strongest associations were observed for the total hip BMD and muscle strength (β: 0.034 g/cm²; 95% CI: 0.022- 0.046 in full model). Also, increased SMI and muscle strength was associated with decreased osteoporosis in crude and adjusted models (P < 0.001).

Conclusions: In this study, it was revealed that the reduction of SMI in elderly patients with diabetes was significantly associated with decreased BMD and TBS. The muscle strength was also associated with BMD and TBS. So, muscle strength and muscle mass should be measured separately ever since both are independently associated with BMD and TBS. Muscle strength and muscle mass were negatively associated with osteoporosis in older people with diabetes. Thus, we should pay more attention to muscle strength training in older people with diabetes, particularly in osteoporotic patients.