A total of 130 non-Western immigrants with prediabetes ( fasting glucose concentration > 5.5 mmol/L or random glucose concentration from 7.8 to 11.1 mmol/L ) and vitamin D deficiency ( serum 25 [ OH ] D concentration < 50 nmol/L ) were randomly assigned after stratification by sex to receive either cholecalciferol ( 1200 IU/d ) or a placebo for 16 wk .