Influence of inflammatory and non-inflammatory rheumatic disorders on the clinical and biological profile of type-2 diabetes

Objective: To study the profile of type-2 diabetes (T2D) in patients with RA or OA.

Methods: This observational, multicentre, cross-sectional study included, over a 24-month period, consecutive patients with adult-onset diabetes and RA or OA. We collected demographics, disease activity and severity indices, current treatments for RA and diabetes, history and complications of diabetes. A systematic blood test was performed, assessing inflammatory, immunological and metabolic parameters. The homoeostasis model assessment (HOMA)2-S was used to assess insulin resistance.

Results: We included 167 patients with T2D, 118 with RA and 49 with OA. RA and OA patients had severe T2D with suboptimal metabolic control and a biological profile of insulin resistance. Insulin resistance was significantly higher in RA than in OA patients after stratification on age, BMI and CS use [HOMA2-S: 63.5 (35.6) vs 98.4 (69.2), P < 0.001]. HOMA2-S was independently associated with DAS28 [odds ratio (OR): 4.46, 95% CI: 1.17, 17.08]. T2D metabolic control was not related to disease activity and functional impairment, but HbA1c levels were independently associated with bone erosions (OR: 4.43, 95% CI: 1.18, 16.61). Treatment with low-dose CSs was not associated with decreased insulin sensitivity or increased HbA1c levels. Treatment with TNF-α inhibitors was associated with increased insulin sensitivity compared with patients not receiving biologics [101.3 (58.71) vs 60.0 (32.5), P = 0.001].

Conclusion: RA patients display severe T2D with inflammation-associated insulin resistance. These findings may have therapeutic implications, with the potential targeting of insulin resistance through the treatment of joint and systemic inflammation.