The Relationship between 25-hydroxyvitamin D Levels, Insulin Sensitivity and Insulin Secretion in Women 3 Years after Delivery

The Role of Vitamin D in the Development of Diabetes Post Gestational Diabetes Mellitus: A Systematic Literature Review

Women diagnosed with gestational diabetes mellitus (GDM) are more likely to later develop diabetes. Evidence from some previous reviews suggests that low vitamin D status during pregnancy increases the risk of developing GDM, but whether vitamin D during pregnancy also influences the risk of diabetes post GDM is less well studied. Thus, the aim of this systematic literature review was to summarize the current available literature on that topic. This review considered observational studies and randomized controlled trials (RCTs). Five databases were searched. The risk of bias of the included studies was assessed. A total of six studies were included: three observational studies and three RCTs. Findings were inconsistent across the six included studies. However, when considering RCTs only, the findings more strongly suggested that vitamin D supplementation during and after pregnancy did not have an influence on markers of diabetes development or diabetes development post GDM. This systematic review highlights inconsistent findings on the associations between vitamin D supplementation or concentration during and after pregnancy and markers of diabetes development or diabetes development post GDM; and although results from randomized interventional studies more strongly suggested no associations, the conclusion holds a high degree of uncertainty.

The Effect of Prior Gestational Diabetes on the Shape of the Glucose Response Curve during an Oral Glucose Tolerance Test 3 Years after Delivery

OBJECTIVE

Monophasic glucose response (MGR) during an oral glucose tolerance test (OGTT) and gestational diabetes mellitus (GDM) are predictors of type 2 diabetes mellitus (T2DM). We investigated the association between current MGR and (1) glucose tolerance during a pregnancy 3 years before and (2) current glucose tolerance status. We also sought (3) other determinants of MGR. Research Design and Methods. We conducted a nested case-control study of GDM (n = 47 early GDM, diagnosed between 16 and 20 weeks of gestation; n = 40 late GDM, diagnosed between 24 and 28 weeks of gestation) and matched healthy controls (n = 37, normal glucose tolerance during pregnancy) all free from diabetes at follow-up 3.4 ± 0.6 years after delivery. Glucose tolerance was determined by 2-hour 75 g OGTT. Monophasic and biphasic groups were defined based on serum glucose measurements during OGTT.

RESULTS

The biphasic group was younger, had lower triglyceride levels and area under the OGTT glucose curve, and was less frequently diagnosed with early GDM (25 vs. 45%, all p < 0.05). Women with a biphasic response also tended to have lower systolic blood pressure (p < 0.1). No differences were found in fasting and 2-hour glucose and insulin levels, or BMI. According to multiple logistic regression, MGR was associated with prior early GDM (OR 2.14, 95% CI 0.92-4.99) and elevated triglyceride levels (OR 2.28, 95% CI 1.03-5.03/log (mmol/l)).

CONCLUSIONS

We found that more severe, early-onset GDM was an independent predictor of monophasic glucose response suggesting that monophasic response may represent an intermediate state between GDM and manifest type 2 diabetes.

Therapies for gestational diabetes and their implications for maternal and offspring health: Evidence from human and animal studies

Obesity prior to and during pregnancy is associated with an increased risk of complications during pregnancy. One of the most common complications of pregnancy is gestational diabetes mellitus (GDM), a condition characterized by hyperglycemia and insulin resistance that is diagnosed in the third trimester of pregnancy. GDM predisposes both mothers and their children to increased obesity and cardiometabolic disorders, namely type 2 diabetes and cardiovascular disease. Current treatments include lifestyle changes and insulin injections, but oral anti-diabetic drugs such as metformin and glyburide are increasingly prescribed as they do not require injections. However, the long-term implications of therapies for diabetes during pregnancy on mothers and their offspring are not fully understood. In this review, we describe current treatments for GDM, including the first line lifestyle interventions such as exercise as well as insulin, glyburides and metformin. We also review selected natural health products that are sometimes used by individuals during pregnancy that could also be an effective therapeutic in pregnancies characterized by obesity or GDM. We focus on both the short- and long-term effects of treatments on the health of mothers and their offspring. We review the current literature from clinical research and animal studies.