Baseline Serum 25-Hydroxy Vitamin D Is Predictive of Future Glycemic Status and Insulin Resistance

Diabetes
Q1
Jun 2008
Citations:672
Influential Citations:17
Observational Studies (Human)
83
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Methods
Population-based prospective cohort (Ely Study, Cambridgeshire, UK). 524 adults without diabetes at baseline (1990–1992), aged 40–69; 214 men and 310 women; randomly selected; follow-up to 10 years with baseline and 10-year measurements of oral glucose tolerance, fasting glucose, fasting insulin, lipids, blood pressure, anthropometry, and serum 25(OH)D with IGF-1 and IGFBP-1/3.
Results
Baseline 25(OH)D was inversely associated with 10-year increases in fasting glucose, 2-h glucose, fasting insulin, HOMA-IR, and metabolic syndrome risk z score after adjustment for age, sex, smoking, BMI, season, and baseline outcome. Per 25 nmol/L increase in baseline 25(OH)D, fasting glucose decreased by 0.05 mmol/L; 2-h glucose decreased by 0.25 mmol/L; fasting insulin decreased by 4.2 pmol/L; HOMA-IR decreased by 0.16; metabolic syndrome risk z score decreased by 0.05. Associations persisted after further adjustment for IGF-1, PTH, calcium, physical activity, and social class. Interactions observed: stronger inverse associations for fasting and 2-h glucose among those with lower IGFBP-1; BMI modified the HOMA-IR association; no interaction with IGF-1. Maintaining adequate vitamin D status may influence future glycemia and insulin resistance; warrants larger prospective studies and randomized trials of vitamin D supplementation to test causality.
Limitations
Modest size; complete-case analysis included about 50% of the initial cohort; potential healthy participant bias; insufficient power to assess diabetes incidence; no data on sun exposure or vitamin D supplement use or repeated vitamin D measures; single geographic population (European Caucasians) limits generalizability; residual confounding possible.

Abstract

OBJECTIVE—Accumulating epidemiological evidence suggests that hypovitaminosis D may be associated with type 2 diabetes and related metabolic risks. However, prospective data using the biomarker serum 25-hydroxyvitamin D [25(OH)D] are limited and ther...