Link between retinopathy and nephropathy caused by complications of diabetes mellitus type 2

While the correlation and chronology of appearance of diabetic nephropathy and retinopathy is well known in diabetes mellitus (DM) type 1 patients, in DM type 2 this correlation is less clear. A retrospective study including 917 patients with type 2 diabetes. Diabetic retinopathy (DR) was diagnosed based on fundus photographs taken with a non-mydriatic camera. Diabetic nephropathy (DN) was diagnosed based on urinary albumin concentration in a morning urine sample. Statistical analysis was performed with a seemingly unrelated regression (SUR) model. Our SUR model is statistically significant: the test for "model versus saturated" is 2.20 and its significance level is 0.8205. The model revealed that creatinine and glomerular filtration rate (GFR) have strong influence on albuminuria, while body mass index (BMI) and HbA1c have less significant impact. DR is affected positively by diabetes duration, insulin treatment, glucose levels, and HbA1c, and it is affected negatively by GFR, triglyceride levels, and BMI. The association between DR and DN was statistically significant and had a unidirectional correlation, which can be explained by chronological order; that is, DN precedes DR. The present study indicates that the level of renal impairment is proportional to the level of damage to the eye. Furthermore, such an association has a chronological aspect; the renal injury precedes retinal damage.