Relationship between fasting serum glucose, age, body mass index and serum 25 hydroxyvitamin D in postmenopausal women

Abstract

Objective Because it has been reported that vitamin D, given to mother or infant, can prevent type I diabetes in children, that diabetes is more common in adults with low serum vitamin D and that insulin secretion and action are related to vitamin D levels in healthy young adults we examined the relationship between serum vitamin D metabolites and fasting serum glucose in patients attending our outpatient clinics. Design Retrospective examination of convenience sample of postmenopausal women attending our osteoporosis clinics. Patients A total of 753 postmenopausal women attending a university hospital outpatient clinic and not on any treatment known to affect glucose metabolism. Measurements Body weight and height, serum 25-hydroxyvitamin D [25(OH)D], serum 1,25-dihydroxyvitamin D [1,25(OH)₂D], serum PTH and fasting serum glucose. Results On simple correlation fasting serum glucose was a positive function of age (P < 0·05), weight (P < 0·001) and body mass index (BMI) (P < 0·001) and a negative function of serum 25(OH)D (P < 0·001), but it was not significantly related to either serum 1,25(OH)₂D, PTH or creatinine. When fasting serum glucose was regressed simultaneously on age, BMI and 25(OH)D, glucose was still an inverse function of 25(OH)D (P = 0·006). Conclusions Fasting serum glucose increased as 25(OH)D levels fell throughout the range of serum 25(OH)D measured but the greatest increase was observed in those with 25(OH)D below 40 nmol/l.