Impact of Vitamin D on Diabetic Kidney Disease in African Americans

Diabetic kidney disease is increasing in prevalence and is associated with significant morbidity and mortality. Health disparities exist in the progression of diabetic kidney disease, with minorities being more affected even when adjusting for treatment, glycemic and hypertensive control, and medical coverage. Secondary prevention of the progression of diabetic kidney disease is hindered by a lack of easily modifiable risk factors. Based on animal and observational human studies, vitamin D deficiency is potentially a novel, modifiable risk factor that may interrupt or delay the progression of diabetic kidney disease through direct effects as well as by helping to ameliorate kidney disease risk factors, such as hyperglycemia, hypertension and inflammation. In addition, based on minorities having a higher prevalence of vitamin D deficiency, it may also potentially impact the differential progression of diabetic kidney disease in minorities. However, clinical trials evaluating the impact of vitamin D supplementation on diabetic kidney disease are lacking. Thus, this pilot study funded as an R03 through the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) has the following specific aims: (1): To evaluate the impact of vitamin D supplementation (vitamin D3 at 400 IU/d versus 4000 IU/d) on the proportion of individuals with progression of albuminuria over 12 months in a sample of African American participants with vitamin D deficiency in a randomized controlled trial. (2): To identify whether kidney disease risk factors such as blood pressure and glycemic control mediate the impact of vitamin D supplementation on the progression of albuminuria over 12 months in a sample of African American participants with vitamin D deficiency in a randomized controlled trial.

Inclusion criteria

• African American race
• Diagnosis of Type 2 Diabetes
• Stage 1 or 2 Kidney Disease with detectable microalbuminuria >4.0 (mg/g) 25(OH)D level <20 ng/ml

Exclusion criteria

• Type 1 diabetes

--> Stage 3 Kidney Disease, or history of dialysis, kidney transplantation or nephrolithiasis

• Unable to provide informed consent or contact information
• Pre-existing calcium or parathyroid condition, including serum calcium >10.2 mg/dL
• Sarcoidosis, active tuberculosis, or malignancy
• Known hypersensitivity to vitamin D or any of its analogues and derivatives
• Current pregnancy or planning to become pregnant in next 15 months