Early impairment of beta-cell function and insulin sensitivity characterizes normotolerant Caucasian women with previous gestational diabetes

Long-Term Metabolic Outcomes after Gestational Diabetes Mellitus (GDM): Results from the Odense GDM Follow-Up Study (OGFUS)

AIMS

To compare metabolic profiles and the long-term risk of metabolic dysfunction between women with previous gestational diabetes mellitus (pGDM) and women without pGDM (non-GDM) matched on age, prepregnancy body mass index (BMI), and parity.

METHODS

In total, 128 women with pGDM (median follow-up: 7.8 years) and 70 non-GDM controls (median follow-up: 10.0 years) completed a 2 h oral glucose tolerance test (OGTT) with assessment of glucose, C-peptide, insulin, and other metabolic measures. Additionally, anthropometrics, fat mass, and blood pressure were assessed and indices of insulin sensitivity and beta cell function were calculated.

RESULTS

The prevalence of type 2 diabetes mellitus (T2DM) was significantly higher in the pGDM group compared to the non-GDM group (26% vs. 0%). For women with pGDM, the prevalence of prediabetes (38%) and the metabolic syndrome (MetS) (59%) were approximately 3-fold higher than in non-GDM women (p's < 0.001). Both insulin sensitivity and beta cell function were significantly reduced in pGDM women compared to non-GDM women.

CONCLUSION

Despite similar BMI, women with pGDM had a substantially higher risk of developing T2DM, prediabetes, and the MetS compared to controls. Both beta cell dysfunction and reduced insulin sensitivity seem to contribute to this increased risk.

Predicting the metabolic condition after gestational diabetes mellitus from oral glucose tolerance test curves shape

The objective of this feasibility study is to predict the metabolic condition in women with a history of gestational diabetes mellitus (GDM) from the shape of oral glucose tolerance test (OGTT) data. The rationale for this approach is that the evolution to a metabolic condition could be traceable in the shape of OGTT curves. 3-h OGTT data of 136 women with follow up, for a total of 401 OGTTs were analyzed. Subjects were classified as having normal (NGT) or non-normal glucose tolerance (NON-NGT), according to the American Diabetes Association criteria. The measured glucose, insulin, C-peptide data and combination of them were used to build up NGT and NON-NGT reference curves. Similarity between reference and individual OGTT-based curves was calculated using the Kullback-Leibler divergence. Our findings suggest that the shape of OGTT curves (1) contains information on the evolution to disease and (2) could be a reliable indicator to predict with high sensitivity (75%) and high specificity (69%) the metabolic condition of women with a history of GDM. In the future, the proposed shape-based prediction could be easily translated to the clinical practice, because it does not require the intervention of an operator specifically trained, thus facilitating its application in a clinical setting and ultimately empowering risk estimation, by improving/complementing the information which is currently adopted for risk stratification after pregnancy with GDM.

Gestational Diabetes Mellitus: An Opportunity to Prevent Type 2 Diabetes and Cardiovascular Disease in Young Women

In women with previous gestational diabetes (pGDM), the risk of developing Type 2 diabetes is greatly increased, to the point that GDM represents an early stage in the natural history of Type 2 diabetes. In addition, in the years following the index pregnancy, women with pGDM exhibit an increased cardiovascular risk profile and an increased incidence of cardiovascular disease. This paper will review current knowledge on the metabolic modifications that occur in normal pregnancy, underlining the mechanism responsible for GDM, the link between these alterations and the associated long-term maternal complications. In women with pGDM, accurate follow-up and prevention strategies (e.g., weight control and regular physical exercise) are needed to reduce the subsequent development of overt diabetes and other metabolic abnormalities related to cardiovascular disease. Therefore, our paper will provide arguments in favor of performing follow-up programs aimed at modifying risk factors involved in the pathogenesis of Type 2 diabetes and cardiovascular disease.

Diabetes related autoimmunity in gestational diabetes mellitus: is it important?

Some GDM women show autoantibody positivity during and after pregnancy and pancreatic autoantibodies can appear for the first time in some patients after delivery. Autoantibody positivity is often accompanied by a high frequency of DR3 and DR4 alleles, which are classically related to the development of type 1 diabetes and, although not all studies agree on this point, by an immunological imbalance expressed by the behaviour of the lymphocyte subpopulation, which can be seen as diabetic anomalies overlapping with the immunological changes that occur during pregnancy. It is worth emphasizing that such patients may develop classical type 1 diabetes during and/or after their pregnancy or they may evolve, often some years after their pregnancy, into cases of latent autoimmune diabetes of adulthood (LADA). Autoimmune GDM accounts for a relatively small number of cases (about 10% of all GDM) but the risk of these women developing type 1 diabetes or LADA is very high, so these patients must be identified in order to prevent the severe maternal and fetal complications of type 1 diabetes developing in pregnancy, or its acute onset afterwards. Since women with autoimmune GDM must be considered at high risk of developing type 1 diabetes in any of its clinical forms, these women should be regarded as future candidates for the immunomodulatory strategies used in type 1 diabetes.

Beta-cell failure in type 2 diabetes mellitus

Diabetes mellitus has been defined as a "group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion, insulin action, or both" and encompasses a wide range of heterogeneous conditions. Common type 2 diabetes mellitus (T2DM) results from a combination of genetic and acquired factors. However, lifestyle factors, particularly overeating and physical inactivity, are the major clinical determinants of T2DM. Insulin resistance is a common feature of T2DM, but it is unlikely to cause T2DM unless progressive loss of beta-cell function develops. Significant reduction in beta-cell function is already present at the time of T2DM diagnosis, and it continuously declines irrespective of treatment. As such, the progressive loss of beta-cell function dictates the rate of worsened glycemic control. Development of progressive deterioration accelerates via gluco- and lipotoxicity, loss of beta-cell function, and shrinkage of beta-cell mass. Understanding the causes for beta-cell failure is therefore of capital importance to develop new and more effective therapeutic strategies.

Influence of gestational diabetes on the long-term control of glucose tolerance

AIMS/HYPOTHESIS

Gestational diabetes (GDM) carries a high risk of subsequent diabetes. We asked what impact prior GDM has on beta cell function and insulin action in women who maintain normal glucose tolerance (NGT) for a long time.

METHODS

Ninety-one women with NGT (aged 41 +/- 8 years, mean+/-SD) were studied (by mathematical modelling of the C-peptide response to an OGTT) 7 [6] years (median [interquartile range]) after the index pregnancy, during which 52 had GDM (pGDM) and 39 had NGT (pNGT). In all women an OGTT had also been performed at 29 +/- 3 weeks of the index pregnancy.

RESULTS

Women with pGDM were matched with women with pNGT for age, familial diabetes, time and weight gain since index pregnancy, parity, BMI (25.4 +/- 3.9 vs 26.8 +/- 6.4 kg/m(2)), and fasting (4.64 +/- 0.56 vs 4.97 +/- 0.46 mmol/l) and 2 h plasma glucose levels (5.91 +/- 1.14 vs 5.91 +/- 1.21 mmol/l). Nonetheless, fasting (49 [29] vs 70 [45] pmol min(-1) m(-2), p < 0.001) and total insulin secretion (32 [17] vs 48 [21] nmol m(-2), p < 0.0001) and beta cell glucose sensitivity (slope of the insulin secretion/plasma glucose concentration-response function) (95 [71] vs 115 [79] pmol min(-1) m(-2) (mmol/l)(-1), p = 0.025) were reduced in the pGDM group compared with the pNGT group, while insulin sensitivity was preserved (424 [98] vs 398 [77] ml min(-1) m(-2)). At index pregnancy, women with pGDM and those with pNGT had similar age and BMI. However, both insulin sensitivity (359 [93] vs 417 [92] ml min(-1) m(-2), p = 0.0012) and the insulin/glucose incremental area ratio (an empirical index of beta cell function; 98 [74] vs 138 [122] pmol/mmol, p = 0.028) were reduced in women with pGDM.

CONCLUSIONS

Even in women who maintain normal insulin sensitivity, impaired beta cell function is carried over into the NGT status several years after a GDM pregnancy.

Gestational diabetes, inflammation, and late vascular disease

Physiological changes of pregnancy include insulin resistance and activation of the innate immunity with an inflammatory response. The working hypothesis is that the sub-clinical inflammation associated with excessive adiposity may favor the development of gestational diabetes (GDM) and Type 2 diabetes and other metabolic abnormalities related to cardiovascular disease later in life. In this paper we review the complex interrelationship among inflammatory markers, metabolic syndrome, and endothelium dysfunction in women with GDM and discuss if women with previous GDM (pGDM) could be considered at risk for cardiovascular diseases. MEDLINE was searched for articles relating GDM and the adipokines (tumor necrosis factor-alpha and adiponectin) as well as the acute-phase inflammatory biomarker C-reactive protein that contribute to the development of diabetic pregnancy and vascular complications. However, to date, in pGDM women no prospective study is available, to corroborate the hypothesis that inflammatory pattern could be taken as predictor of cardiovascular disease later in life. Therefore, our paper should provide arguments to perform follow-up programs to prevent cardiovascular events in women with pGDM. Control of body weight, regular physical exercise are indeed powerful intervention tools able at improving insulin sensitivity and reduce sub-clinical inflammation, both involved in the pathogenesis of cardiovascular disease.