Relationship of vitamin D level and microalbuminuria in type 2 diabetic patients

Background
Great prevalence of patients with type 2 diabetes mellitus (T2DM) has been witnessed in the last decades worldwide. The global prevalence has been estimated to reach 6.4% among adults at the beginning of the current decade. Diabetic nephropathy is considered the most common complication that affects the kidney and plays as a leading cause of end-stage kidney disease. The presence of proteinuria in diabetic patients is a sign of risk. Vitamin D is a multitrait steroid hormone involved in a wide spectrum of cell regulatory and metabolic functions. Multiple diseases were observed to be frequently associated with low levels of vitamin D.
Objective
To estimate the level of vitamin D in T2DM patients, to assess its relation to microalbuminuria, and to estimate the effect of vitamin D replacement on these patients.
Patients and methods
A case–control study was conducted on 50 T2DM patients having microalbuminuria (group 1), 50 T2DM patients with no microalbuminuria (group 2), and 50 apparently healthy persons (group 3) (the control group), Routine tests such as complete blood count, fasting blood glucose, 2 h postprandial blood glucose, glycosylated hemoglobin’, liver enzyme tests [alanine aminotransferase (ALT), aspartate aminotransferase (AST)], kidney function tests (urea, creatinine), lipid profiles [cholesterol, Triglyceride (TG)], serum albumin, calcium, phosphorus, intact parathyroid hormone (PTH), 25-hydroxycholecalciferol in the blood, and urinary albumin/creatinine ratio were done.
Results
The study showed highly statistically significant decrease of vitamin D level in group 1 (diabetes with microalbuminuria) compared with group 2 (diabetes without microalbuminuria) and group 3 (control) (<0.001). A statistically significant negative correlation was found between microalbuminuria and vitamin D (=−0.946). It also showed a highly statistically significant decrease of microalbuminuria after treatment with vitamin D compared with before treatment. There was a highly statistically significant decrease of glycosylated hemoglobin after vitamin D replacement.
Conclusion
This study demonstrated that vitamin D was significantly deficient in diabetic patients in comparison with the control group and it is significantly deficient in T2DM with microalbuminuria compared with T2DM without microalbuminuria. It showed that microalbuminuria was significantly improved after treatment with vitamin D but not to nonmicroalbminuric level. These findings indicated that there is a potential role of vitamin D in diabetic nephropathy pathogenesis.