The planning committee relied on observational
longitudinal data and relevant
intervention studies to estimate a
plausible hazard ratio. In two metaanalyses
that combined data from cohort
studies, the pooled relative risk of type
2 diabetes comparing the highest with
the lowest quartile of 25OHD concentration
was 0.59 (95% CI 0.52–0.67) (31)
and 0.62 (95% CI 0.54–0.70) (7), with
little heterogeneity between studies.
In a short-term trial, the 2,000 IU/day
vitamin D3 supplementation, which
raised blood 25OHD concentration to
31 ng/mL, improved measures of b-cell
function (disposition index) by ;40%
and glycemia (hemoglobin A1c) by
;50% after 4 months (11). After taking
into consideration all published data and