Correlates of muscle strength in diabetes: The study on the assessment of determinants of muscle and bone strength abnormalities in diabetes (SAMBA)

Apart from late motor nerve dysfunction, factors affecting muscle strength in diabetes are largely unknown. This study was aimed at assessing muscle strength correlates in diabetic subjects encompassing a wide range of peripheral nerve function and various degrees of micro and macrovascular complications.Four-hundred consecutive patients with type 1 and 2 diabetes (aged 46.4 ± 13.9 and 65.8 ± 10.3 years, respectively) from the Study on the Assessment of Determinants of Muscle and Bone Strength Abnormalities in Diabetes (SAMBA) were examined for upper and lower body muscle isometric maximal voluntary contraction by dynamometry. Univariate and multivariate regression analyses were applied to identify strength correlates. Isometric force at both the upper and lower limbs was significantly lower in subjects with than in those without any complication. At univariate analysis, it was strongly associated with age, diabetes duration, physical activity (PA) level, cardio-respiratory fitness, anthropometric parameters, surrogate measures of complications, and parameters of sensory and autonomic, but not motor (except amplitude) neuropathy. Multivariate analysis revealed that upper and lower body strength correlated independently with male gender and, inversely, with age, autonomic neuropathy score (or individual autonomic function abnormalities), and vibration perception threshold, but not sensory-motor neuropathy score. Diabetes duration and PA level were excluded from the model.Both upper and lower body muscle strength correlate with measures of diabetic complications and particularly with parameters of sensory and especially autonomic nerve function, independently of diabetes duration and PA level, thus suggesting the involvement of mechanisms other than manifest motor nerve impairment.