Retrospective evaluation of patients with concurrent measurements of HBA1C and vitamin d levels in our institution between 2010-2015

In this study, we aimed to evaluate the frequency and severity of vitamin D deficiency and the relationship between vitamin D and HbA1c levels in patients with concurrent measurements of HbA1c and vitamin D levels in our institution between 2010-2015. 13779 patients' concurrent 25(OH)D and HbA1C were accessed and evaluated retrospectively. 4510 measurements were omitted due to recurrence. Data from 9269 patients were included in final analysis. 25(OH)D, HbA1C (%), creatinine, ALT, albumin, LDL, triglyceride, calcium, phosphorus, magnesium, GGT, parathormone, TSH, free T4 LDH, HDL and urinary calcium levels were analyzed. Glomerular filtration rate was calculated using MDRD 4 formula. Patients were classified as: 0-9.99 ng/ml severe deficiency, 10-19.99 ng/ml deficiency, 20-29.99 ng/ml insufficiency and 30 ng/ml or higher as normal. HbA1C was categorized as normal (<5.69%), pre-diabetes (5.7-6.49%) and diabetes (>6.5%). GFR was further classified as 0-29.99 ml/min; 30-59.99 ml/min; 60 ml/min and higher. Age was grouped as 18-49, 50-64 and 65 or higher. 65 or higher group was further categorized as 65-74 and 75 or higher. Normal value for albumin was considered as 3.5 g/dl. Frequency of severe deficiency was 20.8%; deficiency was 29.8%; insufficiency was 26.1%; and 23.3% of patients had normal vitamin D levels. 50.6% of all patients had vitamin D levels lower than 20 mg/dl and 76.6% had vitamin D levels lower than 30 mg/dl. Vitamin D levels were lower in females and in patients between ages of 18-49. 49.5% of the patients had normal HbA1c levels; 26.7% of the patients had prediabetes and diabetes was present in 23.7% of the study population. In non-diabetic patients vitamin D levels were higher, however, in patients with diabetes, vitamin D showed likelihood to decrease with increased HbA1c levels representing poor control of diabetes. This retrospective analysis supports the previous literature suggesting a negative relation between vitamin D and HbA1c levels. We conclude that it may be beneficial to assess vitamin D levels in all diabetic patients.