The Association between 25-Hydroxyvitamin D and Hemoglobin A1c Levels in Patients with Type 2 Diabetes and Stage 1–5 Chronic Kidney Disease

Abstract

Aim. To examine the relationship between plasma 25-hydroxyvitamin D (25(OH)D) levels and blood hemoglobin A1c (HbA1c) levels in diabetic patients at various stages of chronic kidney disease (CKD). Methods. We screened for data collected between 2003 and 2012. The correlation between 25(OH)D and HbA1c levels was studied in patients categorized according to the severity of CKD and their vitamin D status. A multivariate linear regression model was used to determine whether 25(OH)D and HbA1c levels were independently associated after adjustment for a number of covariates (including erythrocyte metformin levels). Results. We identified 542 reports from 245 patients. The mean HbA1c value was 6.7 ± 1.0% in vitamin D sufficiency, 7.3 ± 1.5% in insufficiency, and 8.4 ± 2.0% in deficiency (P < 0.0001). There was a negative correlation between 25(OH)D and HbA1c levels for the population as a whole (r = −0.387, P < 0.0001) and in the CKD severity subgroups (r = −0.384, P < 0.0001 and r = −0.333, P < 0.0001 for CKD stages 1–3 and 4-5, resp.). In the multivariate analysis, the 25(OH)D level was the only factor associated with HbA1c (P < 0.0001). Conclusion. 25(OH)D levels were negatively correlated with HbA1c levels independently of study covariates.

The Association of Vitamin D Status and Vitamin D Replacement Therapy with Glycemic Control, Serum Uric Acid Levels, and Microalbuminuria in Patients with Type 2 Diabetes and Chronic Kidney Disease

“…Our findings also revealed a significant role of higher HbA1 c in predicting a decrease in vitamin D levels, in agreement with previous studies [7,23,24] .…”

“…This lower level of 25(OH)D among diabetic patients and higher HbA1 c in cases of hypovitaminosis D than with vitamin D sufficiency was also reported in other studies on diabetic patients with various stages of CKD [7,19,21,22] . Our findings also revealed a significant role of higher HbA1 c in predicting a decrease in vitamin D levels, in agreement with previous studies [7,23,24] .…”

“…A significantly low level of vitamin D was tified products, and/or supplements [4,5] . Most patients with T2DM have low 25(OH)D levels, while high levels are associated with a lower risk of incident diabetes [6,7] . Reduced nephron mass and/or 1-α hydroxylase enzyme activity has been shown to be associated with a decline in 1.25 dihydroxyvitamin D, i.e., 1.25(OH) 2 D, levels in patients with chronic kidney disease (CKD) [8] .…”

“…Reduced nephron mass and/or 1-α hydroxylase enzyme activity has been shown to be associated with a decline in 1.25 dihydroxyvitamin D, i.e., 1.25(OH) 2 D, levels in patients with chronic kidney disease (CKD) [8] . Hence, it has been suggested that renal status be considered in studies involving vitamin D status among T2DM patients [7] .…”

Spectrum of Vitamin D in Type 2 Diabetes Mellitus: A Hospital Based Study

“…Similar observations were made by Farshad et al, who reported that mean HbA1c value was 6.7 ± 1.0% in vitamin D sufficiency, 7.3 ± 1.5% in insufficiency, and 8.4 ± 2.0% in deficiency subjects ( < 0.0001) and that there was a negative correlation between vitamin D and HbA1c levels ( = −0.387, < 0.0001). 17 The inverse relationship of vitamin D with HbA1c may indicate that hypovitaminosis D may be associated with the long-term abnormal carbohydrate metabolism in type 2 diabetes. In this context, it is suggested that supplementation of vitamin D may be useful in the management of diabetes.…”