Adults with type 2 diabetes who had symptomatic knee osteoarthritis with clinically meaningful pain were less likely to meet recommended glycemic targets, even after adjustment for key confounders, according to a cross-sectional study conducted in Canada.
Patients with knee osteoarthritis (OA) and average pain severity of at least 20 on a 0-to-100 numeric rating scale had approximately 40% lower odds of meeting an A1c target of 7.0% or less compared with those without painful knee OA.
Researchers recruited adults aged 45 years or older with a physician diagnosis of type 2 diabetes from outpatient diabetes clinics at 3 academic hospitals in Toronto between March 2022 and August 2023. Participants completed structured online questionnaires assessing sociodemographic characteristics, comorbidities, diabetes treatments, and joint symptoms. Symptomatic knee OA was defined using National Institute for Health and Care Excellence clinical criteria, which include age threshold, activity-related knee pain, and brief or absent morning stiffness, while excluding inflammatory arthritis to reduce misclassification. Glycemic control was assessed using hemoglobin A1c values abstracted from clinic records within 3 months of questionnaire completion, with target control defined as an A1c of 7.0% or lower.
The analytic cohort included 351 participants with a mean age of 66.2 years; 50.7% were women, and more than 80% had postsecondary education. Overall, 28.5% met criteria for symptomatic knee OA, and 43.9% achieved glycemic targets. In unadjusted analyses, knee OA overall was associated with lower odds of achieving target glycemic control; however, this association was attenuated and no longer statistically significant after adjustment for age, gender, education level, and body mass index (BMI).
In contrast, analyses incorporating symptom severity demonstrated a persistent association. The researchers stated, “we found those with symptomatic knee OA who had a minimum threshold of average pain severity (greater than or equal to 20/100) were about 40% less likely to be at target glycemic control.” This association for painful knee OA remained statistically significant after full multivariable adjustment. In unadjusted analysis, knee OA with walking difficulty was associated with lower odds of achieving target glycemic control, but this association did not remain statistically significant after adjustment for age, gender, education level, and BMI.
Participants with knee OA reported higher BMI, greater functional impairment, and higher levels of fatigue, sleep disturbance, and depressive symptoms than those without OA.
The study's authors also pointed out that the cross-sectional design precluded causal inference and allowed for potential reverse associations. The study was designed to evaluate HbA1c as a continuous measure and may have been underpowered when glycemic control was analyzed as a binary outcome. Confidence intervals were wide, and the highly educated, clinic-based sample may limit generalizability. Income data and objective measures of physical activity and body composition were unavailable, noted the study's authors.
The study was funded by a resident research grant from the Physician Services Incorporated Foundation.
Source: Arthritis Care & Research
