Effect of type 2 diabetes mellitus on bone mineral density in patients with rheumatoid arthritis

Background: RA affection of bone manifests as low bone mineral density (BMD), generalised osteoporosis and increased risk of fragility fractures. Whereas, Type 2 Diabetes Mellitus (T2DM) produces many micro and macro vascular complications, its effects on bone and bone density is not very clear. The effect of coexistent RA and T2DM on BMD has not been well studied. Objective: The aim of this study was to investigate the effect of T2DM on BMD in patients with newly diagnosed RA. Methods: Patients diagnosed as RA were assigned to undergo BMD testing. Patients with T2DM were gathered from this population and formed a separate group. Healthy controls were drawn from subjects who came for a check-up. BMD was done with the GE Lunar DPX machine. Mean T Scores at spine, femur neck and total femur were recorded. Multivariate analysis was performed to compare T scores at various sites in the 3 groups. Age, gender, and steroid use were checked as confounding factors. Results: A total of 449 patients were diagnosed as RA during the period of 48 months. Of these, 337 (M-56, F-321) diagnosed as RA who had their BMD examined were enrolled in the study. Five hundred and one (M-248, F-253) healthy controls were enrolled. The mean T score values at femur neck, femur total and spine were -1.2+0.9, -0.8+1, -1.2+1.3 for controls, -2.4+0.8, -2.2+0.9, -2.9+0.9 for patients with RA and -1.7+1, -1.3+1, -1.7+1.2 for patients with RA+T2DM. The T scores at all sites in patients with additional T2DM were significantly better than those with only RA but significantly less than compared to controls. Similar results were obtained when separate analyses were done for males and females. Conclusion: Coexisting T2DM partly negates the low BMD measures and present with significantly higher values as compared to RA alone. In patients with this co morbidity, the BMD measures should be read with caution. With increasing evidence of diabetics having higher fragility fracture risk, measures other than the standard BMD need to be investigated which can quantify the exact fracture risk in patients with RA and T2DM