Glycemic Impact on Knee Osteoarthritis Symptoms on Physical, Radiographic, and Inflammatory Markers among Individuals Aged 50 and Over with Diabetes

This study explores hyperglycemia's influence on knee osteoarthritis (KOA) related symptoms, physical performance, physical activity level, radiographic severity, and inflammation in older adults. Prolonged hyperglycemic states contribute to advanced glycation end-product (AGE) formation, which worsens KOA symptoms. Capillary blood glucose (CBG) and glycated hemoglobin A1C (HbA1C) levels are commonly used in laboratory tests for glycemic assessment, offering distinct advantages and limitations. Participants were divided into good and poor glycemic control groups based on their CBG and HbA1C levels. KOA clinical severity and physical activity were measured using the knee injury and osteoarthritis outcome score (KOOS) and international physical activity questionnaire. Physical performance was measured with hand grip strength, gait speed, time-up-and-go (TUG), and 5 times sit-to-stand (5STST). Knee X-rays were performed, and serum enzyme-linked immunosorbent assay (ELISA) analysis was conducted for IL-1β, IL-4, CRP, NF-κB, and AGE. Three hundred recruited participants (mean age [SD] = 66.40 years (5.938) with CBG, of fasting blood sugar > 7.0 mmol/L and random blood sugar > 11.1 mmol/L, (N = 254) were compared with KOOS pain (p=0.008) and symptoms (p=0.017) and 5STST (p=0.015); while HbA1c > 6.3% (N = 93) was compared with 5STST (p=0.002), and AGEs (p=0.022) based on Mann Whitney U test. Logistic regression revealed significant associations between glycemic control and lower limb muscle strength, radiological severity, laboratory markers, and between glycemic status and KOOS pain and symptoms. However, these associations did not remain significant after adjusting for BMI. Poor glycemic status alone was associated with better function in sport and recreation domains after antidiabetic medication adjustment, suggesting anti-inflammatory and analgesic effects that masked the effect of high blood sugar. Future studies could explore the predictive ability of glycemic assessment for poor knee function and physical performance while accounting for the effects of the medication.