BackgroundAssociation between diabetes mellitus (DM) and risk of osteoarthritis (OA) can be confounded by body mass index (BMI), a strong risk factor for both conditions. We evaluate the association between DM or hyperglycaemia with OA using systematic review and meta-analysis.MethodsWe searched PubMed and Web of Science databases in English for studies that gave information on the association between DM and OA. Two meta-analysis models were conducted to address: (1) risk of DM comparing subjects with and without OA and (2) risk of OA comparing subjects with and without DM. As far as available, risk estimates that adjusted for BMI were used.Results31 studies with a pooled population size of 295 100 subjects were reviewed. 16 and 15 studies reported positive associations and null/ negative associations between DM and OA. 68.8% of positive studies had adjusted for BMI, compared with 93.3% of null/negative studies. In meta-analysis model 1, there was an increase prevalence of DM in subjects with OA compared with those without (OR 1.56, 95% CI 1.28 to 1.89). In meta-analysis model 2, there was no increased risk of OA (OR 1.14, 95% CI 0.98 to 1.33) in subjects with DM compared with those without, regardless of gender and OA sites. Comparing subjects with DM to those without, an increased risk of OA was noted in cross-sectional studies, but not in case-control and prospective cohort studies.ConclusionsThis meta-analysis does not support DM as an independent risk factor for OA. BMI was probably the most important confounding factor.

Purpose: Inflammation has been shown to underlie the pathogenesis of osteoarthritis. We evaluated the association between inflammatory biomarkers in peripheral blood and severity of knee osteoarthritis (KOA). Methods: We performed a cross-sectional study of 139 participants with frequent knee pain, evaluated radiographic severity according to the Kellgren-Lawrence (KL) grading, joint space narrowing (JSN) and osteophyte (OST) formation, and clinical severity according to the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). We measured five inflammatory markers: plasma (p) IL-1Ra, IL-1b, IL-18, serum (s) CD14, hsCRP and five bone and cartilage biomarkers urine (u) CTX-II, (s) HA, COMP, CTX-I, PIIANP. Associations between various biomarkers with severity of KOA were evaluated, with and without adjustment for age, gender and body mass index (BMI). Results: (p) IL-1Ra was negatively associated with radiographic severity assessed by KL of index knee (Spearman rho (r)¼-0.197, P¼ 0.021), OST of index knee (r¼-0.217, P¼ 0.011), JSN of index knee (r¼-0.172, P¼ 0.045) and KL sum score of both knees (r¼-0.180, P¼ 0.035), after adjustment for age, gender and BMI. Other inflammatory biomarkers were not associated with radiographic severity after adjustment. The cartilage degradation markers (u) CTXII and (s) COMP were modestly associated with radiographic severity after adjustment. In multivariate models, (s) hsCRP and the bone and cartilage biomarkers, but not the inflammatory biomarkers, were associated with radiographic severity. Conclusions: Among the inflammatory biomarkers in peripheral blood, IL-1Ra was negatively associated with radiographic severity of KOA. This supports the role of inflammation in the pathogenesis of OA, and these biomarkers are potential candidates for evaluation of their ability to prognosticate progression of KOA in longitudinal studies.