Diabetes predicts severe osteoarthritis independently of BMI

By Sally Robertson, B.Sc.Oct 15 2012

Diabetes is a strong predictor for the development of severe osteoarthritis (OA) requiring joint arthroplasty, report researchers.

"Our study is the first to show that Type 2 diabetes predicts severe OA independent of age, sex, and BMI [body mass index]," say Georg Schett (University of Erlangen-Nuremberg, Erlangen, Germany) and colleagues.

Traditionally, mechanical factors have been though to underlie more rapid joint degeneration in obese individuals. However, this concept has been challenged by a link between obesity and OA in non-weight bearing joints, suggesting that metabolic changes directly enhance the risk for OA, explain Schett and team.

In a population-based cohort study of 927 men and women, 69 individuals (mean BMI 27.0 kg/m²) were diagnosed with diabetes (fasting glucose ≥7mmol/L) at baseline in 1990.

Follow-up examinations conducted every 5 years until 2010 showed that 13 arthroplasties were performed due to severe symptomatic hip/knee OA in these individuals, corresponding to an intervention rate of 17.7 per 1000 person-years.

This compared with 73 interventions carried out in those who did not have baseline diabetes, corresponding to a rate of 5.3 per 1000 person-years.

As reported in Diabetes Care, the hazard ratio (HR) for joint failure requiring arthroplasty among the diabetic individuals was 3.8 in unadjusted Cox regression analysis.

Interestingly, Type 2 diabetes remained significantly associated with the need for arthroplasty, at an HR of 2.1, after adjustment for a variety of important risk factors, including age and BMI.

To account for weight gain during follow up, analysis was conducted using BMI data that had been updated at each 5-year time point. This sensitivity analysis yielded similar results, with diabetes associated with a 2.2-fold increased risk for arthroplasty.

Furthermore, results were similar in men and women and after adjustment for smoking, physical activity, and serum parameters such as C-reactive protein.

The team notes that the mean Type 2 diabetes duration was significantly longer in diabetes patients who required arthroplasty that in those who did not.

To further elaborate the association between Type 2 diabetes and OA, a number of cross-sectional analyses were performed. The team reports that there were more severe clinical symptoms of OA and structural joint changes in individuals with Type 2 diabetes than in those without the condition.

"Our study fosters the concept that OA is part of the metabolic syndrome," says the team. "This notion shifts the traditional perception of OA as a degenerative joint disease based on continuous mechanical overload to a metabolic etiopathogenesis."

The findings may therefore add a novel, modifiable, and highly prevalent risk condition for the development of OA, conclude the researchers.

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