Maintenance of long-term adequate levels of vitamin d lowers HbA1c in African American patients with type 2 diabetes.

Objectives: We examined the long-term effects of enhanced Vitamin D (VitD) supplementation on parameters of type 2 diabetes mellitus (T2DM): serum hemoglobin A1c, low density lipoprotein, high density lipoprotein, and triglyceride for the purpose of determining beneficial VitD levels in T2DM African Americans (AA).

Design And Methods: Following inclusion criteria, retrospective charts of patients aged > or = 30 years were reviewed. VitD supplementation was given to patients as part of drug regimen over a three year continuum. Pearson correlations were used to assess the relationship between VitD levels and levels of each parameter. Repeated measure analysis of variance was conducted to identify difference in mean levels of each parameter between years with VitD included as part of therapy.

Results: Vitamin D supplementation was inversely associated with HbA1c (r = -.286, P = .031). No correlation was found between levels of VitD and levels of LDL, HDL or TG. Hemoglobin A1c levels were found to be significantly different under VitD treatment between year 1 (mean VitD 24.75 microg/mL, mean HbA1c 9.15%, P = .000) and year 2 (mean VitD 33.84 microg/mL, mean HbA1c 7.91%, P = .000) and between year 1 and year 3 (mean VitD 34.46 microg/mL, mean 7.98% HbA1c P = .000).

Conclusion: In T2DM AA, significant improvements in HbA1c are obtained with enhanced VitD supplementation as part of drug regimen over time. Our investigation provides the first known evidence of a relationship between enhanced VitD supplementation as part of a pre-existing medical regimen taken over long term and determinants of T2DM in a group of overweight and obese AA with T2DM.