CHICAGO – High-dose vitamin D2 supplementation shows promise for the treatment of chronic pain among women with type 2 diabetes and comorbid depression, according to a single-arm pilot study known as the Sunshine Study.
The vitamin D2 supplementation at 50,000 IU/week for 6 months also was associated with significant improvement in major depressive disorder in this uncontrolled study, Sue M. Penckofer, Ph.D., reported at the annual scientific sessions of the American Diabetes Association.
Dr. Sue Penckofer
This was a small, hypothesis-generating study of a relatively low-cost and safe potential therapy for a common clinical condition. The encouraging results have led to a $1.5 million grant from the National Institutes of Health for a considerably larger 4-year randomized controlled trial due to begin later this year, said Dr. Penckofer, professor of nursing at Loyola University in Maywood, Ill.
The pilot study included 46 women with type 2 diabetes, major depressive disorder, and vitamin D insufficiency as evidenced by their mean baseline serum level of 18 ng/mL. They averaged 54.6 years of age, with a 7.8-year history of diabetes and a mean hemoglobin A1c of 6.8%. Twenty-eight of the women had neuropathic pain involving their legs and 34 had sensory pain, with numbness or tingling in their feet and/or legs.
After 6 months of weekly vitamin D supplementation, the subjects’ mean vitamin D blood level had climbed to 38 ng/mL. Their median score on the Center for Epidemiologic Studies Depression Scale improved from 26.8 at baseline to 12.2 and their depression rating on the Patient Health Questionnaire (PHQ-9) improved from 11.5 to 5.2, although their antidepressant medication regimens were not required to be held constant.
Scores on the neuropathic pain subscale of the Diabetes Symptom Checklist improved from a baseline of 3.2 to 1.8 at 3 months and 2.1 at 6 months. Scores on the sensory pain subscale improved from 7.3 at baseline to 5.0 at 3 months and 5.9 at 6 months. These favorable trends didn’t attain statistical significance in such a small study population, but patients in the top half of the group in terms of neuropathic or sensory pain did show statistically significant improvement over time. Those in the high baseline neuropathic pain group went from an average score of 5.2 at enrollment to 2.5 at 3 months and 2.8 at 6 months. Similarly, the high sensory pain subgroup improved from a baseline score of 10.6 to 6.8 at 3 months and 6.9 at 6 months, according to Dr. Penckofer.
The Sunshine Study was funded by the National Institute of Diabetes and Digestive and Kidney Diseases. Dr. Penckofer reported having no conflicts of interest.