Lower serum 25-hydroxyvitamin D levels are associated with impaired glomerular filtration rate in type 2 diabetes patients

• Published in: Therapeutic advances in endocrinology and metabolism Vol. 11; p. 2042018820930904
• Main Authors: Dall’Agnol, Angélica, Brondani, Letícia de Almeida, Cancelier, Vítor da Agostim, Camargo, Eduardo Guimarães, Silveiro, Sandra Pinho
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 2020; Sage Publications Ltd; SAGE Publishing
• Subjects: 25-Hydroxyvitamin D; Albumins; Chemiluminescence; Chromium radioisotopes; Confidence intervals; Diabetes; Diabetes mellitus; Diabetes mellitus (non-insulin dependent); Epidemiology; Epidermal growth factor receptors; Ethylenediaminetetraacetic acids; Evaluation; Generalized linear models; Glomerular filtration rate; Kidney diseases; Kidneys; Original Research; Poisson density functions; Regression analysis; Regression models; Renal function; Risk analysis; Risk factors; Robustness (mathematics); Statistical analysis; Statistical models; diabetic kidney disease; 25(OH)D; albuminuria; urinary albumin excretion; glomerular filtration rate; vitamin D
• ISSN: 2042-0188; 2042-0196
• DOI: 10.1177/2042018820930904

Background:
25-Hydroxyvitamin D [25(OH)D] deficiency has been implicated as a possible risk factor for the onset and progression of diabetes kidney disease (DKD). The aim of this study was to evaluate the interaction between levels of 25(OH)D and DKD in type 2 diabetes mellitus (DM) patients.
Methods:
Cross-sectional design, outpatient type 2 DM. Glomerular filtration rate (GFR) was measured by 51Cr-EDTA and estimated by Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), urinary albumin excretion (UAE) by immunoturbidimetry, and 25(OH)D by chemiluminescence. Receiver operating characteristic (ROC) curve analysis and generalized linear model (Poisson robust regression estimator) were used to assess the interaction between 25(OH)D levels and renal function.
Results:
A total of 114 type 2 DM patients aged 60 ± 10 years, 49 males (43%), DM duration 22 ± 10 years, with GFR > 60 ml/min/1.73 m2 were evaluated. Patients with GFRs 60–90 (n = 50) had significantly lower 25(OH)D levels than individuals with GFRs > 90 ml/min/1.73 m2 (n = 64), respectively 40 ± 20 versus 48 ± 20 nmol/l, p = 0.027. This difference was more pronounced for older individuals (39 ± 20 versus 54 ± 23 nmol/l, respectively), and Poisson robust regression disclosed that lower 25(OH)D [Poisson regression (PR) = 0.989, confidence interval (CI): 0.978–0.999, p = 0.034], and advanced age (PR = 1.050, CI: 1.007–1.096, p = 0.023) were significantly associated with the lower GFR category, adjusted for seasons. ROC curve analysis showed that the cutoff point of 25(OH)D of 41 nmol/l was associated with lower GFR [area under the curve (AUC) = 0.694, p = 0.009]. CKD-EPI estimated GFR (eGFR) was not associated with 25(OH)D in any analysis. There was no difference in 25(OH)D levels between patients with elevated UAE as compared with normoalbuminuric ones (44 ± 21 versus 46 ± 19 nmol/l, p = 0.587).
Conclusion:
Lower levels of 25(OH)D are associated with decreased GFR in patients with type 2 DM, especially in older patients, with no evidence of interaction with UAE levels.