The distinct musculoskeletal phenotypes of Type 1 and Type 2 diabetes: a sonographic characterization of enthesopathy burden

Abstract Objective Musculoskeletal complications represent a significant burden in diabetes, yet the distinct presentation between Type 1 (T1DM) and Type 2 Diabetes Mellitus (T2DM) remains under-characterized. This study aimed to evaluate and quantify the burden of rheumatic manifestations and subclinical enthesopathy in these two distinct clinical phenotypes. Methods We conducted a cross-sectional analysis of 65 patients (21 T1DM, 44 T2DM). A comprehensive rheumatological evaluation assessed adhesive capsulitis (defined as painful restriction of active and passive motion in ≥ 2 planes), knee osteoarthritis (per American College of Rheumatology clinical classification criteria), cheiroarthropathy, and soft tissue rheumatism. High-resolution musculoskeletal ultrasound evaluated five bilateral entheseal sites using the Glasgow Ultrasound Enthesitis Scoring System (GUESS). Effect sizes (Cohen’s d) and 95% Confidence Intervals (CI) were calculated to assess the magnitude of intergroup differences. Results The T2DM phenotype was characterized by older age and higher BMI compared to T1DM. T2DM patients exhibited a markedly higher prevalence of adhesive capsulitis, knee osteoarthritis, and anserine bursitis. Ultrasound revealed a substantially higher enthesopathy burden in the T2DM group, with a mean GUESS score of 6.8 ± 2.1 compared to 1.1 ± 0.2 in T1DM. The effect size for the difference in enthesopathy scores (Cohen’s d = 3.29) exceeded the effect size for the age difference (d = 2.79), suggesting that the observed structural burden may not be fully explained by age alone. Available HbA1c data showed similarly suboptimal glycemic control in both groups. Conclusion T2DM was associated with a higher burden of structural entheseal abnormalities and higher GUESS scores compared with T1DM. These findings may reflect the combined influence of obesity, metabolic factors, and age. Interpretation should consider baseline demographic differences between groups and the broad clinical definitions employed.