High-dose vitamin D therapy and prolonged partial remission of type 1 diabetes - a case report.

Clinical trials demonstrating β-cell protection by high-dose vitamin D supplementation have led to the adoption of adjunctive vitamin D therapy in stage 3 type 1 diabetes (T1D). We present the case of a 12-year-old male child who received high-dose vitamin D therapy from 1-27 months following his diagnosis with T1D. His serum 25-hydroxyvitamin D rose from 25 ng/mL to 65 ng/dL within 3 months and remained >40 ng/mL. Hemoglobin A1c (A1c) decreased from 13.8% at diagnosis to persistently <7%. Time in range remained >70% for 24 months, and insulin-dose adjusted A1c (IDAA1c), the clinical marker of partial clinical remission, decreased from 17 to <9 for the duration of therapy. This description of persistence of partial clinical remission (PR), defined as IDAA1c ≤9, for 27 months in a child receiving adjunctive high-dose vitamin D therapy is a build up from our randomized controlled trial of high-dose vitamin D where we demonstrated significant blunting of temporal rise in A1c and IDAA1c over a 12-month period. This prolonged remission by high-dose vitamin D is clinically significant as it positions vitamin D as an affordable therapeutic agent to prolong PR and reduce the short- and long-term complications of T1D. Long-term studies are needed to determine the ultimate duration of these beneficial effects.