Abstract

Aims: To identify whether baseline vitamin D status is associated
with future glycaemic control. To assess whether vitamin D status
differs between two groups when classified by glucose control
(above or below 6.1mmol/l: cut-off point for impaired fasting
glucose; World Health Organization (WHO), 2006).
Methods: Following an overnight fast 104 participants (female
53; male 51) with varying levels of glucose control attended the
laboratory on three occasions, with each visit separated by
6 months. Venous blood samples were analysed for vitamin D
(25(OH)D3), fasting plasma glucose (FPG), fasting plasma insulin
(FPI) and HbA1c.
Results: Significant negative correlations were observed between
25(OH)D3 at 0 months and HbA1c at 12 months (r = �0.241,
n=75, p=0.04) and FPI at 12 months (r = �0.225, n=81, p=0.04),
but not FPG at 12 months (r = �0.105, n=80, p=0.35). Participants
with impaired fasting glucose or Type 2 diabetes (n=47; FPG
8.0 � 2.1mmol/l) had significantly lower 25(OH)D3 concentrations
(35.1 � 20.2 vs 45.6 � 24.7nmol/l) than those with normoglycaemia
(n=57; FPG 5.1 � 0.4mmol/l) (U=884.000, p=0.03).
Conclusions: Participants with lower vitamin D had poor glucose
control compared to those with higher vitamin D concentrations on
the day of testing and at 12 months follow-up. Whilst further studies
are required to determine cause and effect, these findingsmay provide
additional evidence of a protective effect of vitamin D in relation to
glycaemic control and the development of Type 2 diabetes.