The Association Between Glycated Hemoglobin (HbA1c) Level and Vitamin D Level in Diabetes Mellitus Patients: A Cross-Sectional Study

Background: Prior research has established noteworthy correlations between inadequate glycemic management and a multitude of problems in individuals diagnosed with diabetes mellitus (DM). Methods: This is a cross-sectional retrospective study that was conducted at the Jeddah Center for the Care of Diabetes and Blood Pressure Patients, Jeddah, Kingdom of Saudi Arabia. The medical records of patients diagnosed with DM between 2015 and 2022 were identified and reviewed for the purpose of this study. Pearson correlation coefficient was used to examine the correlation between glycated haemoglobin (HbA1c) and vitamin D levels. Multiple linear regression analysis was applied to identify the association between HbA1c and vitamin D levels. Results: A total of 152 patients were included in this study. The mean HbA1c level for the patients in this study was 8.2% (SD: 1.7). The median vitamin D level for the patients was 20.9 ng/ml (interquartile range (IQR): 13-30.4). More than half of the patients (n= 92; 60.5%) were found to have vitamin D insufficiency. Pearson correlation coefficient identified that there is an inverse correlation between the level of HbA1c and vitamin D level (r= -0.21 (95%CI -0.36 to -0.06; p-value= 0.007). Multiple linear regression analysis (adjusting for age and type of DM) identified that poor glycaemic control has a negative association with vitamin D level (regression coefficient (B) = -0.027; 95%CI -0.053 to - 0.001; p-value= 0.039). Conclusion: Poor glycaemic control is associated with vitamin D deficiency in DM patients. It is recommended that patients with DM adhere to their medications and maintain a healthy lifestyle in order to manage their condition. This will improve their overall health, specifically their vitamin D status.