25 OH vitamin D level and its association with insulin resistance in patients with gestational diabetes

Aim: Gestational diabetes mellitus (GDM) is defined as ß cell dysfunction and insulin resistance with first onset during pregnancy. Women having a history of GDM are at increased risk of developing type 2 diabetes in later life. In the literature, there are contradictory data stating that pregnant women are more prone to vitamin D deficiency and that there is a relation between vitamin D deficiency and insulin resistance in pregnant women. In the present study, our aim was to determine the status of vitamin D by measuring 25OH vitamin D level and to evaluate the relation between 25OH vitamin D level and insulin resistance in patients diagnosed with gestational diabetes. Materials and Methods: A total of 200 pregnant women (100 having GDM and 100 having NGT) were included in the study. Routine gestational diabetes screenings were carried out by 75 gram 2 hour OGTT and GDM diagnosis was made based on the IADPSG criteria. Fasting serum samples were collected and glucose, insulin, calcium, phosphorus, magnesium, total protein, albumin, ALP, 25OH vitamin D and PTH levels were determined. Insulin resistance was calculated using HOMA-IR method. 25OH vitamin D level was categorized based on previously published criteria: sufficient vitamin D level defined as ?30 ng/ml, vitamin D insufficiency defined as 20-29.99 ng/ml and vitamin D deficiency defined as <20 ng/ml. Results: 25OH vitamin D averages were found to be similar in pregnant women with GDM and NGT (31.33±20.64 ng/ml vs. 29.51±22.66 ng/ml, p=0.553). In terms of frequency of vitamin D deficiency, there was no statistically significant difference between GDM group and the controls (%36 vs. %44, p=0.505). It was observed that vitamin D deficiency did not have a statistically significant effect on the risk of developing GDM (p=0.361) and that vitamin D averages were similar in diabetic pregnant women having insulin resistance (HOMA-IR>2.7) and having no insulin resistance (HOMA-IR<2.7) (33.67±18.36 ng/nl vs. 30.67±21.31 ng/ml, p=0.551). Conclusion: Frequency vitamin D deficiency ratios were similar in pregnant women with GDM and the controls. It was shown that the effect of vitamin D deficiency on the risk of developing GDM was not statistically significant and that there was no statistically significant relation between 25OH vitamin D level and insulin resistance in pregnant women having GDM. Keywords: Gestational diabetes, vitamin D status, insulin resistance.