The importance of optimal 25-hydroxyvitamin D levels in the glycemic control of older adults with type 2 Diabetes Mellitus: Data from the study on aging and longevity EELO

Introduction: Optimal serum levels of vitamin D are of great importance, especially in populations with comorbidities such as Diabetes Mellitus (DM). Objective: The study evaluated the relationship between hypovitaminosis D and glycemic control in older adults with type 2 DM. Methods: Cross-sectional and prospective study, part of the EELO project (Study on Aging and Longevity), conducted in Southern Brazil. Glycated hemoglobin (diabetes ≥6.5%) and serum levels of vitamin D (25(OH)D) were evaluated. Hypovitaminosis D was determined using cutoff points <20 and <30 ng/mL). Multivariate logistic regression was used to assess the risk of having uncontrolled DM. Results: Of the 120 older adults included in the study, aged between 60 and 87 years, 74.2% were women, 66.7% used hypoglycemic medications and 75.8% exhibited uncontrolled diabetes. An inverse correlation was observed between the levels of 25(OH)D and glycated hemoglobin (rS=-0.19, p=0.037), suggesting that low levels of vitamin D are associated with poor glycemic control in diabetic individuals. The prevalence of hypovitaminosis D when using the cutoff points of <20 and <30 ng/mL were 34.2% and 75.0%, respectively. The odds ratio (OR) analysis showed that individuals with 25(OH)D<20ng/mL have almost 4 times more risk of having uncontrolled DM (OR:3.94; CI95%:1.25-12.46, p=0.02) when compared to the older adults with sufficient levels of vitamin D. Conclusion: The results indicate that the optimal serum levels currently recommended for 25(OH)D should preferably be 30 ng/mL or higher to contribute to better glycemic control in older adults with type 2 DM.