Reduced Muscle Strength Associates with Insulin Resistance in Type 2 Diabetes Patients with Osteoarthritis.

CONTEXT Type 2 diabetes associates with greater risk for musculoskeletal disorders, yet its impact on joint function remains unclear. OBJECTIVE We hypothesized that patients with type 2 diabetes and osteoarthritis would exhibit musculoskeletal impairment, which would associate with insulin resistance and distinct microRNA profiles. DESIGN, PARTICIPANTS & METHODS Participants of the German Diabetes Study with type 2 diabetes (T2D, n=39) or normal glucose tolerance (CON, n=27), both with (+OA) or without osteoarthritis (-OA) underwent intravenous glucose tolerance and hyperinsulinemic-euglycemic clamps tests. Musculoskeletal function was assessed by isometric knee extension strength (KES), grip strength, range of motion (ROM), balance skills, while neural function was measured by nerve conductance velocity (NCV). Arthritis-related symptoms were quantified using WOMAC questionnaire, serum arthritis-related microRNA using qPCR. RESULTS Insulin sensitivity was lower in T2D+OA vs T2D-OA (4.4±2.0 vs. 5.7±3.0 mg*kg -¹*min -¹) and in CON+OA vs CON-OA (8.1±2.0 vs. 12.0±2.6 mg*kg -¹*min -¹, both p<0.05). In T2D+OA, KES and ROM were 60% and 22% lower than in CON+OA, respectively (both p<0.05). Insulin sensitivity correlated positively with KES (r=0.41, p<0.05) among T2D, and negatively with symptom severity in CON and T2D (r=-0.60 and r=-0.46, respectively, p<0.05). CON+OA and T2D+OA had inferior balance skills than CON-OA, whereas NCV was comparable in T2D+OA and T2D-OA. Expression of arthritis-related microRNAs was upregulated in T2D compared to CON, but downregulated in CON+OA compared to CON-OA (p<0.05), and did not differ between T2D+OA and T2D-OA. CONCLUSIONS Musculoskeletal impairment and osteoarthritis-related symptoms are associated with insulin resistance. Type 2 diabetes can mask changes in arthritis-related microRNA profiles.Clinicaltrials.gov (Identifier number: NCT01055093).