RESUMO
Objective:This was a retrospective study to compare the serum 25-hydroxy vitamin D [25(OH)D], retinol binding protein 4(RBP-4) and other clinical data in type 2 diabetes mellitus (T2DM) patients with or without diabetic nephropathy (DN) and to explore the clinical significance of these indicators in DN.Methods:1946 T2DM patients were enrolled in this study. The T2DM patients were divided to group with diabetic nephropathy (DN group) and without diabetic nephropathy (NDN group). According to the urine albumin to creatinine ratio (UACR), DN patients were further divided into microalbuminuria subgroup (UACR 30~300 mg/g) and massive proteinuria subgroup (UACR> /g). Clinical characteristics including serum 25(OH)D, RBP-4 and other biochemical indicators were collected.Results:Compared with NDN group, DN group showed longer disease duration, older age and higher levels of HbA1c, RBP-4, hs-CRP, TC and TG; 25(OH)D and HDL-C in DN group were lower than those in NDN group ( P<0.05). Within DN group, massive proteinuria subgroup showed higher RBP-4, younger age and lower 25(OH)D and HDL-C than microalbuminuria subgroup ( P<0.05). After adjusted for age, gender and disease duration in DN, partial correlation analysis showed that 25(OH)D is positively correlated with eGFR, and negatively correlated with RBP-4 and UACR ( P<0.05). UACR is positively correlated with RBP-4 and TC, and negatively correlated with eGFR (all P<0.05). eGFR is negatively correlated with RBP-4, TC and UACR (all P<0.05). Multivariate logistic regression showed that disease duration, HbA1c, RBP-4 and hs-CRP are risk factors for DN, and 25(OH)D is the protective factor for DN. Conclusions:Decreased 25(OH)D and increased RBP-4 are associated with increased DN risk in T2DM patients, and also associated with exacerbated albuminuria and deteriorated renal function in DN patients. There is a negative correlation between 25(OH)D and RBP-4 in DN. Therefore, it is necessary to strengthen the monitoring of serum 25(OH)D and RBP-4 and enhance vitamin D supplementation in T2DM patients to prevent the occurrence and delay the progression of diabetic nephropathy.