Graded association of muscle strength with all-cause and cause-specific mortality in older adults with diabetes: Prospective cohort study across 28 countries

BACKGROUND: The worldwide prevalence of diabetes is increasing, particularly among older adults. Understanding the association between muscle strength and mortality in this population is crucial for developing targeted exercise recommendations.

OBJECTIVES: To assess the prospective association of muscle strength with mortality in older adults with diabetes.

METHODS: From the Survey of Health, Ageing and Retirement in Europe (SHARE) study, spanning 28 countries, we included 16 149 diabetic adults aged 50 years and older (mean age 68.2 [standard deviation, SD, 9.2] years). Participants fulfilled two criteria: (1) diabetes diagnosis (ever) and (2) current use of diabetes medication. Muscle strength was assessed using handgrip dynamometry (unit: kg). Using time-varying Cox regression with restricted cubic splines, we determined the prospective association of muscle strength with all-cause and cause-specific mortality, controlling for various confounders.

RESULTS: Over a mean follow-up of 5.9 years (SD 3.8), 2754 participants died (17%). Using the median level of muscle strength as reference (30 kg), lower and higher levels were associated in a curvilinear fashion with higher and lower all-cause mortality risk, respectively. The 10th percentile of muscle strength (17 kg) showed a hazard ratio (HR) of 1.65 (95% confidence interval (CI) 1.53-1.79). The 90th percentile (47 kg) of muscle strength showed a HR of 0.55 (95% CI 0.49-0.63). A somewhat similar pattern, with varying strength of associations, was seen for mortality due to cardiovascular disease (CVD), respiratory disease, severe infectious disease, digestive system disease and cancer.

CONCLUSION: Muscle strength is gradually and inversely associated with all-cause and cause-specific mortality risk in older adults with diabetes. As muscle strength is highly adaptable to resistance training at all ages, the present findings highlight the importance of improving muscle strength in older adults with diabetes.