Endocrine Abstracts

Introduction: Impaired fasting glucose (IFG) is defined as being present in those whose fasting blood glucose level is consistently elevated above normal, but is not high enough to be considered as having diabetes mellitus. Impaired glucose tolerance (IGT) is defined as being present in those whose second hour plasma glucose level is higher than normal, but is not high enough to be considered as having diabetes mellitus. Low serum 25-hydroxyvitamin D levels are associated with glucose intolerance, diabetes mellitus, and metabolic syndrome. To date, the literature is conflicting regarding the relationship between vitamin D levels and prediabetes. Our aims in this study were to evaluate serum 25-hydroxyvitamin D levels and their association with prediabetic metabolic patterns.

Material and methods: Participants were 220 patients from our endocrine clinic: 85 with isolated IFG, 50 with isolated IGT, 85 with both IFG and IGT, and 80 normoglycaemic healthy subjects with similar age, gender, and BMI. A detailed history and physical examination of the patients were performed. 25-hydroxyvitamin D, calcium, phosphorus, albumin and PTH levels were measured. 25-hydroxyvitamin D levels were categorised as adequate if >30 ng/ml, insufficient if 20–30 ng/ml, and deficient if <20 ng/ml.

Results: We found significantly lower 25-hydroxyvitamin D levels in the IGT (11.7±6.5 ng/ml) (P<0.007) and IFG+IGT patients (13.2±7.2 ng/ml) compared to controls (16.6±9.8 ng/ml) (P<0.047). Lower 25-hydroxy vitamin D levels were associated with a higher risk of IGT (OR 2.57, 95% CI 1.01–6.53, P=0.043). 25-hydroxyvitamin D levels were similar in the control group and IFG group. Significant differences in 25-hydroxyvitamin D levels between the IFG group, IGT group and IFG+IGT group were not found.

Conclusion: Vitamin D insufficiency and deficiency are associated with IFG, IGT, and combined IFG and IGT. However, the only statistically significant association was that between 25-hydroxyvitamin D levels and IGT.

Disclosure: This work was supported by Celal Bayar University Research Foundation (grant number 2011-024).