Gestational diabetes mellitus an updated overview

Authors: E Chiefari B Arcidiacono D Foti A Brunetti

Publish Date: 2017/03/10

Volume: 40, Issue: 9, Pages: 899-909

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Abstract

The clinical and public health relevance of gestational diabetes mellitus GDM is widely debated due to its increasing incidence the resulting negative economic impact and the potential for severe GDMrelated pregnancy complications Also effective prevention strategies in this area are still lacking and controversies exist regarding diagnosis and management of this form of diabetes Different diagnostic criteria are currently adopted worldwide while recommendations for diet physical activity healthy weight and use of oral hypoglycemic drugs are not always uniform In the present review we provide an update of current insights on clinical aspects of GDM by discussing the more controversial issuesGestational diabetes mellitus GDM the most common metabolic disorder of pregnancy is defined as “the type of glucose intolerance that develops in the second and third trimester of pregnancy resulting in hyperglycemia of variable severity” 1 As a consequence of increasing obesity prevalence and advancing maternal age the incidence of GDM is increasing worldwide constituting a major economic burden for the public health care system 1 2 In fact GDM confers an increased risk for severe pregnancy complications for both mother and child including cesarean delivery shoulder dystocia macrosomia and neonatal hypoglycemia 3 In addition women with GDM have a substantially increased risk to develop type 2 diabetes mellitus T2DM and cardiovascular disease CVD after pregnancy 4 5 while their offspring are at increased risk for the development of obesity and T2DM early in life 6 Therefore strategies addressed to optimize management of GDM are mandatory These should include effective prevention and proper diagnosis and treatmentAs reported before the prevalence of GDM in a population of pregnant women usually reflects the prevalence of T2DM in that population 2 As a consequence of the unfavorable global shift toward a western lifestyle of overeating and sedentary living a pandemic diffusion of T2DM is occurring today throughout the entire world 1 which contributes importantly to the dramatic increase in the incidence of GDM rate 2 Nevertheless the exact worldwide prevalence of GDM remains unknown as systematically synthesized data on this are lacking 2 and the only available information is that GDM prevalence is largely variable among countries and even among regions within a country ranging from 06 to 15 depending on the race/ethnicity and socioeconomic status of individuals 2 Aboriginal in Australia Middle Eastern Syrian Lebanese Iraqi Iranian or Afghanistan and Pacific Islanders women are the major at riskgroups for GDM 2 Recent epidemiological studies indicate that the prevalence of GDM is over 9 in the United States of America 7 whereas native Americans Asians Hispanics and AfricanAmerican women are at higher risk for GDM than nonHispanic white women 7 In Asian countries GDM ranges from 30 to 212 7 while in India GDM is more common in women living in urban areas than in those living in rural areas 7 On the other hand recent evidence indicates that the prevalence of GDM may vary according to seasons with higher values during the summer season than in the winter season 8Also it must be considered that a further push toward the increasing prevalence of GDM is derived from the adoption of tighter diagnostic criteria for GDM which have been recently introduced by the International Association of the Diabetes and Pregnancy Study Groups IADPSG 9 These new criteria recommend a universal 75g oral glucose tolerance test OGTT screening for pregnant women which employs more rigorous cutoffs of glucose level The adoption of these newer criteria resulted in a considerable increase in GDM prevalence 10 reaching 275 in Southern Italy 11 and 419 in North Indian women 12There are significant changes in maternal metabolism during the course of pregnancy 13 During the first phase these changes are mostly anabolic changes with the progressive increase of maternal adipose tissue whereas in late pregnancy the catabolic changes prevail with increased lipolysis and an increase in glycemia insulinemia postprandial fatty acid levels and decreased maternal fat stores These alterations are induced at least in part by hormones and other mediators secreted by placenta which facilitate the occurrence of a physiological condition of peripheral insulin resistance 13 that can be worsen by both advanced maternal age and prepregnancy overweight Table 1 two conditions that have become typical in Western countries The effects of pregnancy on glucose homeostasis are generally alleviated following delivery of the placenta so that glycemia returns to normal levels within 6–12 weeks postpartum The negative influence of prepregnancy overweight or obesity on GDM is underlined by the observation that physical activity both before pregnancy and in early pregnancy by ameliorating body weight loss and insulin resistance is inversely associated with the risk of GDM 14 When insulin secretion does not increase adequately to counterbalance the insulinresistant state of the second half of pregnancy maternal glucose intolerance appears and may contribute to the increased risk for developing GDM Fig 1 13 Thus βcell secretory impairment represents a critical defect in the pathophysiology of GDM The defect in βcell function is not specific to pregnancy as it may exist before and after pregnancy and in most cases is progressive conferring a high risk of overt diabetes after the index pregnancy 15 Thus as already pointed out GDM could be seen as an early stage of T2DM which appears during pregnancy 15

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