A review of individual patients from three trials reported a reduction of 3% in absolute risk of pre-diabetes.1 The comparable doses from two studies were 80,000 units 4 weekly and 120,000 units 4 weekly; the NZ option is 1.25 mg cholecalciferol tablet = 50,000 units once per month.
There was an improvement with higher blood levels, with the greatest reduction with a blood level of ≥ 125 mmol/l. There appeared to be no adverse effects, but studies were not powered to detect these.
The NNT to prevent diabetes is 30 (compared with 7 for intensive lifestyle and 14 with metformin). It was mainly effective in those with BMI < 31.3 Kg/m. The study ethnicities were European 50% and Asian 33%), so no Māori or Pacific patients.