Vitamin D status in children and its association with glucose metabolism in northern China: a combination of a cross-sectional and retrospective study.

Objectives: This study aimed to explore the vitamin D status of children in northern China and the association between vitamin D and glucose metabolism.

Design: Cross-sectional study was conducted among child participants and retrospective study designs were conducted among adult participants.

Setting And Participants: Both studies were recruited from Harbin, 326 children were included in children's study, 8469 adults were included in adult study.