Comparison of microvascular complications and inflammatory markers according to vitamin D levels in patients with diabetes mellitus

Objective: Diabetes Mellitus (DM) is a global health problem characterized by hyperglycemia caused by pancreatic β-cell loss and/or dysfunction and peripheral resistance to insulin, in which genetic, autoimmune and environmental factors play a role. Microvascular complications such as diabetic nephropathy (DN), diabetic retinopathy (DR), diabetic neuropathy (DN) and macrovascular complications such as ischemic heart disease and stroke may occur. Studies have shown that microvascular and macrovascular complications of diabetes mellitus are a consequence of the chronic inflammatory process. Vitamin D has numerous non-calcemic effects and has been shown to have favorable effects on microvascular complications, both anti-inflammatory and through its ability to suppress the renin angiotensin aldosterone (RAAS) system. Ratios of complete blood count values such as neutrophil to lymphocyte ratio (NLR) can be used as cost-effective, easily calculated systemic inflammatory markers. In this study, we aimed to compare vitamin D with diabetic neuropathy, diabetic nephropathy and systemic inflammatory parameters. Materials and Methods: In our retrospective study, 489 patients aged 18-90 years with a diagnosis of diabetes mellitus who applied to Afyonkarahisar Health Sciences University Hospital Endocrinology and Metabolic Diseases outpatient clinics between 01.01.2020-31.07.2023 were included. Patients were divided into 3 groups according to vitamin D level as vitamin D < 10 ng/mL deficiency, 10 ng/mL ≤ vitamin D < 20 ng/mL insufficiency and 20 ng/mL ≤ vitamin D sufficiency. Age, gender, duration of diabetes, routine biochemical parameters after at least 8 hours of fasting; fasting blood glucose, glycated hemoglobin A1c, serum creatinine level, eGFR, lipid profile; triglycerides, HDL-cholesterol, total cholesterol, LDL-cholesterol, hemogram parameters; ratios of hemogram parameters to each other and to other parameters (neutrophil-lymphocyte ratio, monocyte-HDL ratio, monocyte lymphocyte ratio, platelet lymphocyte ratio), spot urine microalbumin/creatinine ratio, serum vitamin D level, diabetic neuropathy and diabetic nephropathy among microvascular complications were analyzed. Results: The mean age of patients with diabetes mellitus was 61.97 ± 9.90 years. Of the DM patients, 154 (31.5%) were male and 335 (68.5%) were female. The mean age at diabetes was 10.86 ± 6.52 years and the mean body mass index (BMI) was 33.87 ± 6.81 kg/m2. There were 78 patients in the deficient group (< 10ng/ml), 188 patients in the insufficient group (10-20 ng/ml) and 223 patients in the sufficient group (≥20 ng/ml). Albuminuria levels were 77.06 ± 206.45 mg/g, 65.53 ± 214.30 mg/g and 26.42 ± 83.63 mg/g, respectively, and there was a statistically significant difference between these 3 groups(0,002). There was a very low negative correlation between vitamin D and albuminuria level (r=-0,163, p<0,001). There was no significant difference in inflammatory parameters (NLO, MHO, MLO, PLO) between the 3 groups according to vitamin D level (p>0,05). Vitamin D level was 20.36 ± 9.29 ng/ml in patients without neuropathy and 18.50 ± 9.15 ng/ml in patients with neuropathy and was significantly higher (p=0,032). Conclusion: This study showed that 54.4% of Type 2 DM patients were deficient or insufficient of vitamin D. Reduced vitamin D levels were associated with impaired glycemic control. Increased albuminuria, increased frequency of diabetic nephropathy and a significant increased in diabetic neuropathy observed in the vitamin D deficient group. NLO, MHO, MLO were associated with nephropathy and neuropathy in Type 2 DM. Keywords: Diabetes Mellitus, Diabetic Nephropathy , Diabetic Polyneuropathy, Vitamin D, Neutrophil Lymphocyte Ratio, Monocyte High Density Lipoprotein Ratio, Monocyte Lymphocyte Ratio, Platelet Lymphocyte Ratio