The bidirectional relationship between diabetes and poor muscle function in older adults: data from two population-based studies

Background: Skeletal muscle dysfunction contributes significantly to disability, which is one of the most common complications of diabetes in older adults. We aimed to assess whether diabetes was associated with a steeper muscle strength decline, and whether lower strength is related to a higher diabetes incidence in older adults. Methods: A prospective analysis of data from two Italian population-based studies in older adults (the Invecchiare in Chianti and Progetto Veneto Anziani studies). Diabetes was assessed at baseline and after a median of 4.4 (first follow-up) and 6.3 years (second follow-up) using multiple sources of information. Muscle function was assessed as handgrip strength. Results: The sample comprised 3927 participants (58.6% females) with a mean age of 75.5 years (29.6% aged ≥80 years). After adjusting for potential confounders, the decline in muscle strength among individuals with diabetes exceeded that of those without diabetes by 0.70 kg (95% CI: -1.30 to - 0.11) at the first follow-up and by 0.84 kg (95% CI: -1.61 to - 0.07) at the second follow-up. In those taking oral antidiabetics, this association was even stronger. Over a median 5-year follow-up, 186 incident diabetes cases were recorded. In a multivariable Cox regression, each 1-SD higher in the handgrip/body weight ratio was associated with an 20% lower likelihood of incident diabetes (95%CI 0.68-0.95, n = 3102). Conclusions: These findings demonstrate an independent circular relationship between diabetes and skeletal muscle strength. In older people, muscle dysfunction may be a long-term diabetes complication. Whether increasing muscle strength might reduce diabetes risk remains to be determined.