Prevalence of systemic co-morbidities in patients with various grades of diabetic retinopathy.

Background & objectives: Though diabetes affects multiple organs, most studies highlight the occurence of only one complication in isolation. We conducted a hospital-based study to estimate the co-existence of significant systemic co-morbid conditions in patients with varying grades of diabetic retinopathy. Methods: A total of 170 consecutive patients with diabetic retinopathy were prospectively recruited for the study between June 2009 to June 2010 at a tertiary care eye centre in north India. Retinopathy was graded by fundus biomicroscopy and fundus photography and classified into three categories (mild-moderate nonproliferative retinopathy, proliferative retinopathy requiring only laser and proliferative retinopathy requiring surgery). Nephropathy was classified by calculating the six variable estimated glomerular filtration rate (eGFR) for all patients. Nerve conduction studies and clinical assessment were used to determine presence of neuropathy. Co-existence of macrovascular disease and peripheral vascular disease was also ascertained. Results: The percentages of patients with overt nephropathy in the three groups were 19.2, 38.0 and 41.2, respectively. Significant linear trends were observed for serum creatinine (P=0.004), albumin (P=0.017) and eGFR (P=0.030). A higher per cent had abnormal nerve conduction on electrophysiology than that diagnosed clinically (65.4 vs. 44.2, 76.0 vs. 40.0 and 64.8 vs. 48.6, respectively). The odds ratio (95% CI) for co-existence of nephropathy, neuropathy, CVA (cerebrovascular accidents) and PVD (peripheral vascular disease) was 2.9, 0.9, 4.8 and 3.5, respectively. Independent of retinopathy severity, patients with clinically significant macular oedema (CSME) had a higher percentage of nephropathy (pP < 0.005). Interpretation & conclusions: The co-existence of overt nephropathy, nerve conduction based neuropathy and macrovascular co-morbidity in patients with early grades of diabetic retinopathy was significant. Screening for overt nephropathy by eGFR should be considered in all patients with clinically significant macular oedema.