High Prevalence of Vitamin D Deficiency and Its Association with Early Markers of Kidney Injury in Type 2 Diabetes:A cross-sectional study

Background Given the unclear role of vitamin D (VD) deficiency in early kidney injury, this study aimed to investigate the association between VD status and diabetic nephropathy (DN) in patients with type 2 diabetes. Methods This cross-sectional study included 909 patients with type 2 diabetes mellitus who received treatment at the Department of Endocrinology and Metabolism of the Fourth People’s Hospital of Shenyang between July and December 2022. Participants were grouped according to serum 25-hydroxyvitamin D [25(OH)D] levels: <10, 10–20, 20–30, and ≥ 30 ng/mL. Clinical data, including blood pressure, body mass index, waist circumference, fasting blood glucose, lipid profiles, glycated hemoglobin (HbA _1c ), C-reactive protein, and urinary albumin-to-creatinine ratio (UACR), were collected. DN was defined based on UACR levels and estimated glomerular filtration rate (eGFR) after excluding other causes of kidney disease. Associations between VD levels and clinical parameters were assessed using linear and logistic regression analyses. Results The prevalence of VD deficiency (< 20 ng/mL) among patients with type 2 diabetes was 81.7%, with 97% exhibiting insufficiency (< 30 ng/mL) and a mean VD level of 14 ± 6.9 ng/mL. Simple linear regression analysis revealed a correlation of VD levels with age, uric acid, and urinary albumin-to-creatinine ratio (P < 0.05). Furthermore, patient stratification by VD levels revealed significant differences in age and uric acid levels among the groups (P < 0.05). Additionally, grouping based on albumin-to-creatinine ratio exhibited significant differences in VD levels (P < 0.05). Conclusions The prevalence of VD deficiency is extremely high among patients with type 2 diabetes and serves as an early indicator of kidney disease, highlighting the need for early screening and potential intervention.