Diabetes mellitus (DM), which is defined as high blood glucose level, is a major public health issue worldwide. An enormous amount of data has been gathered regarding DM as populations have been living with it for more than a decade; however, continually updating our knowledge of DM remains important. Comorbidities are among the major challenges associated with DM. Poorly controlled DM, especially type 2 DM (T2DM), is considered a risk factor for many diseases, including but not limited to chronic kidney disease (CKD). Complications might appear over time as the aging process changes body functions; moreover, a significant number of antidiabetic medications are eventually cleared by the kidneys, thereby increasing the burden on kidney function and placing diabetic patients at risk. The significantly high number of patients with uncontrolled diabetes resulting from kidney disease shows the impact of this condition on the quality of life of patients. This review presents an overview of the pathophysiology, etiology, and prevalence of CKD and abnormal renal parameters correlated with poorly controlled T2DM, with an emphasis on clinical studies involving the association between vitamin D insufficiency/deficiency and CKD among patients with T2DM.
The overall aim of this study is to determine the prevalence of vitamin D deficiency and its association with diabetic nephropathy in elderly patients with type 2 diabetes mellitus. This study is a single center retrospective cross-sectional design conducted at private medical center. The study group included all patients (18 years or older) suffering from type 2 diabetes mellitus that attended the diabetic clinic from September 2019 to January 2021. The main outcome variable is a trough level of (<20 ng/mL) for 25OHD. The patients were categorized as having diabetic nephropathy based on estimated glomerular filtration rate (eGFR). Total glycated hemoglobin (HbA1c), creatinine serum, Alb: Cr ratio, total cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were compared between vitamin D deficiency groups. Univariate and multivariate logistic regression was used to investigate the association between vitamin D deficiency and other significant anthropometric and biochemical factors. A p value < 0.05 was chosen as the criterion to make decisions regarding statistical significance. Among the 453 diabetic patients included in study, 48.6% (n = 220) were male and 51.4% (n = 233) were female. The mean age ± S.D of the patients was 54.5 ± 10.6 years old. Out of 453 diabetic patients, 71.1% (95% CI: 66.9%-75.3%) had vitamin D deficiency (25OHD < 20 ng/mL). There was a statistically significant association between 25OHD level and diabetic nephropathy in elderly patients with type 2 diabetes mellitus. Diabetic patients with e-GFR < 60 mL/min more likely to have vitamin D deficiency (p < 0.001). Similarly, individuals with Alb: Cr ratio > 30 mg/g were more likely to have vitamin D deficiency (p < 0.001). Moreover, diabetic patients with serum creatinine > 1.8 mg/dL were more likely to have vitamin D deficiency (p < 0.001). The study revealed a high prevalence of vitamin D deficiency in elderly patients with type 2 diabetes mellitus. A significant association was reported between 25-hydroxyvitamin D, e-GFR and Alb: Cr ratio.