Elsevier

Endocrine Practice

Volume 18, Issue 2, March–April 2012, Pages 185-193
Endocrine Practice

Original Article
Vitamin D Insufficiency in Diabetic Retinopathy

https://doi.org/10.4158/EP11147.ORGet rights and content

ABSTRACT

Objective

To assess the relationship between vitamin D status and diabetic retinopathy.

Methods

A clinic-based, cross-sectional study was conducted at Emory University, Atlanta, Georgia. Overall, 221 patients were classified into 5 groups based on diabetes status and retinopathy findings: no diabetes or ocular disease (n = 47), no diabetes with ocular disease (n = 51), diabetes with no background diabetic retinopathy (n = 41), nonproliferative diabetic retinopathy (n = 40), and proliferative diabetic retinopathy (PDR) (n = 42). Patients with type 1 diabetes and those taking > 1,000 IU of vitamin D daily were excluded from the analyses. Study subjects underwent dilated funduscopic examination and were tested for hemoglobin A1c, serum creatinine, and 25-hydroxyvitamin D [25(OH)D] levels between December 2009 and March 2010.

Results

Among the study groups, there was no statistically significant difference in age, race, sex, or multivitamin use. Patients with diabetes had lower 25(OH)D levels than did those without diabetes (22.9 ng/mL versus 30.3 ng/mL, respectively; P < .001). The mean 25(OH)D levels, stratified by group, were as follows: no diabetes or ocular disease = 31.9 ng/mL; no diabetes with ocular disease = 28.8 ng/mL; no background diabetic retinopathy = 24.3 ng/ mL; nonproliferative diabetic retinopathy = 23.6 ng/mL; and PDR = 21.1 ng/mL. Univariate analysis of the 25(OH) D levels demonstrated statistically significant differences on the basis of study groups, race, body mass index, multivitamin use, hemoglobin A1c, serum creatinine level, and estimated glomerular filtration rate. In a multivariate linear regression model with all potential confounders, only multivitamin use remained significant (P < .001).

Conclusion

This study suggests that patients with diabetes, especially those with PDR, have lower 25(OH)D levels than those without diabetes. (Endocr Pract. 2012; 18:185-193)

Section snippets

INTRODUCTION

Diabetes mellitus continues to be a tremendous health burden in the United States. In 2007, diabetes was estimated to involve 23.6 million people, or 7.8% of the population (1). The number of people diagnosed with diabetes is expected to increase to 48.3 million by the year 2050 (2). Diabetes is also the leading cause of new blindness in patients 20 to 74 years of age (1). Although it has been well established that intensive blood glucose control can lower the risk of microvascular

PATIENTS AND METHODS

The Emory University (Atlanta, Georgia) School of Medicine Institutional Review Board approved this study, and all work was conducted in accordance with the Health Insurance Portability and Accountability Act regulations. This research followed the tenets of the Declaration of Helsinki. A clinic-based cross-sectional study was designed at the Emory Eye Center.

Study Subject Characteristics

Results of the univariate analysis across the study groups are shown in Table 1. There was no statistically significant difference between the study groups with regard to age, race, sex, or multivitamin use. There was, however, a statistically significant difference in the study groups with regard to BMI (P = .003), A1C (P < .001), hypertension (P < .001), and macrovascular disease (P = .002). Among those patients with diabetes, there was also a statistically significant difference in the duration

DISCUSSION

There were 2 purposes of this cross-sectional study. The first was to assess the relationship between vitamin D status and diabetic retinopathy, and the second was to establish baseline data from which a larger prospective clinical study could be designed. It was found that patients with type 2 diabetes, particularly those with PDR, had lower vitamin D levels than did those without diabetes. Moreover, there was a higher percentage of study subjects with vitamin D insufficiency in the diabetic

CONCLUSION

This study showed that patients with type 2 diabetes mellitus, especially those with PDR, had lower 25(OH)D levels and were more likely to have vitamin D insufficiency than were patients without diabetes. The use of multivitamins was also somewhat protective against vitamin D insufficiency. Although this is the largest study to date designed to assess this relationship, larger studies are needed to confirm these findings. In addition, studies are needed to assess whether the treatment of

DISCLOSURE

The authors have no multiplicity of interest to disclose.

ACKNOWLEDGMENT

This study was supported in part by a grant to Emory University Eye Center from Research to Prevent Blindness, Inc., and through a departmental grant from the National Eye Institute of the National Institutes of Health (EY06360). The sponsors had no role in the design or conduct of this research.

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