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Diabetes in pregnancy

Prevention and management

Benefits and harms of treating gestational diabetes mellitus: A systematic review and meta-analysis for the US Preventive Services Task Force and the National Institutes of Health Office of Medical Applications of Research

This systematic review evaluated whether treatment of gestational diabetes mellitus modifies outcomes of mothers and their offspring and whether it is associated with any harms.

Summary points
  • Outcomes of treating gestational diabetes mellitus (GDM) are not well-established.
  • To summarize evidence about the maternal and neonatal benefits and harms of treating GDM, a systematic review of trials and cohort studies published in English from 1995 to May 2012 was conducted.
  • Of 14,428 citations, five randomized controlled trials and six retrospective cohort studies met inclusion criteria. All studies compared diet modification, glucose monitoring, and insulin as needed with standard care.
  • There was moderate evidence for fewer cases of preeclampsia, shoulder dystocia, and macrosomia in the treated group.
  • Current research does not show a treatment effect of GDM on clinical neonatal hypoglycemia or future poor metabolic outcomes of the offspring.
  • There is little evidence of short-term harm of treating GDM other than an increased demand for services.

Hartling L et al. Ann Intern Med 2013; 159: 123–129. doi: 10.7326/0003-4819-159-2-201307160-00661

Management of type 1 diabetes in pregnancy

This review discusses the current standards of care and latest research for type 1 diabetes in the preconception, pregnancy, and postpartum periods.

Summary points
  • Patients with type 1 diabetes mellitus (T1DM) who are of reproductive age should be informed about the increased risks associated with pregnancy to ensure that pregnancies are planned.
  • Early counseling, pregnancy planning, good glycemic control, and a multi-specialist approach to care before and during pregnancy can all improve pregnancy outcomes for mothers with T1DM and their infants.
  • The goals of preconception care should be tight glycemic control with an A1C <7% and as close to 6% as possible without significant hypoglycemia.
  • Pregnant patients with T1DM have insufficient insulin, causing higher maternal glucose levels. Tight glycemic control should be continued throughout the pregnancy with an A1C goal <6 % to reduce the occurrence of maternal, fetal, and neonatal complications.
  • More research is needed in this patient population, especially in the areas of preconception counseling and education, ways to predict and decrease preeclampsia risk, insulin dosing with relation to meal times during pregnancy, medication use during lactation in women with T1DM, and how to improve breastfeeding rates, among others.

Feldman AZ, Brown FM. Curr Diab Rep 2016; 16: 76. doi: 10.1007/s11892-016-0765-z

Management of pregnant women with type 2 diabetes mellitus and the consequences of fetal programming in their offspring

This review examines the state of the science on preconception and pregnancy management of women with type 2 diabetes.

Summary points
  • Women with type 2 diabetes who become pregnant need preconception counseling, preconception weight management and weight loss, proper weight gain during pregnancy, self-monitoring of blood glucose levels, medication, medical nutrition therapy, and exercise.
  • It is imperative that healthcare providers focus on the health of young women and work with them to manage overweight and obesity early in life to prevent development of prediabetes and type 2 diabetes later in life.
  • Healthcare providers need to talk with young women not only about their own health status but also the future health status of their unborn baby and the risks of fetal programming.
  • Once a woman develops type 2 diabetes, a balance between weight management, optimal glycemic control, medical nutrition therapy, and exercise can create the ideal environment for the woman to conceive and optimize outcomes for her and her unborn child.
  • Prevention of fetal programming by tight glycemic control will be instrumental in breaking the cycle of obesity, diabetes, and complications.

Berry DC et al. Curr Diab Rep 2016; 16: 36. doi: 10.1007/s11892-016-0733-7

The role of lifestyle interventions in the prevention of gestational diabetes

Epidemiologic data linking healthy lifestyle choices to reduced risk of gestational diabetes mellitus (GDM) are compared with interventional trials of diet and exercise to prevent GDM.

Summary points
  • Obesity is a rising concern in women of reproductive age. Lifestyle interventions introduced in pregnancy have the potential to prevent the development of gestational diabetes mellitus (GDM) and other complications.
  • The observational literature supports a link between unhealthy lifestyle habits, obesity, and GDM and most trials of lifestyle interventions to prevent GDM have been negative.
  • Reasons for negative studies may include lack of power, lack of intervention uptake, and severity of placenta-mediated insulin resistance.
  • Dietary approaches appear to be more successful than exercise or a combination of diet and exercise at decreasing GDM.
  • Physicians should continue to recommend against excessive weight gain in pregnancy as it has been associated with large for gestational age neonates, non-elective Cesarean section, and post-partum weight retention.
  • Future studies should be powered for a reduction in GDM, monitor lifestyle changes closely, and include a psychological component in the intervention.
  • Unfortunately at this time, there is insufficient evidence to recommend for a specific lifestyle program to prevent GDM.

Halperin IJ, Feig DS. Curr Diab Rep 2014; 14: 452. doi: 10.1007/s11892-013-0452-2

The use of insulin analogs in pregnancy

A discussion of the role of insulin analogs in pregnancy and whether there are differences between women with type 1 diabetes, type 2 diabetes or gestational diabetes.

Summary points
  • Excellent glycemic control is essential in pregnancy to optimize maternal and fetal outcomes.
  • Insulin lispro and insulin aspart are safe in pregnancy and may improve post-prandial glycemic control in women with type 1 diabetes.
  • However, a lack of data indicating improved fetal outcomes would suggest that there is no imperative to switch to a short-acting analog where the woman's diabetes is well controlled with human insulin.
  • Most studies of insulin glargine in pregnancy are small, retrospective and include women with pre-existing diabetes and gestational diabetes. There appear to be no major safety concerns and so it seems reasonable to continue insulin glargine if required to achieve glycemic control.
  • The greater evidence base supports the use of insulin detemir as the first-line long-acting analog in pregnancy but the lack of definitive fetal benefits means that there is no strong need to switch a woman who is well controlled on neutral protamine Hagedorn insulin.

Lambert K, Holt RIG. Diabetes Obes Metab 2013; 15: 888–900. doi: 10.1111/dom.12098

Using oral agents to manage gestational diabetes: What have we learned?

Research suggests that glyburide and metformin alone or in conjunction with insulin may be safe for the treatment of gestational diabetes (GDM). This paper summarizes data on the use of these oral agents for GDM.

Summary points
  • Neither glyburide nor metformin are approved by the Food and Drug Administration (FDA) for use in pregnancy and both are classified as category B during pregnancy.
  • However, glyburide has become the preferred medical treatment for gestational diabetes (GDM) in the USA, surpassing insulin. Yet, many studies report significant failure rates.
  • Both a large retrospective study and a recent meta-analysis of randomized controlled trials (RCTs) indicated higher rates of macrosomia and neonatal hypoglycemia for women treated with glyburide compared with insulin.
  • A large glyburide-versus-insulin RCT with adequate power to detect neonatal and pubertal outcomes is therefore needed.
  • As glyburide crosses the placenta, additional studies are needed to evaluate the effect of exposure of the fetal pancreas to an insulin secretagogue and the long-term effects on weight and cardiometabolic status during childhood and adolescence.
  • A large, well-designed RCT of metformin versus insulin demonstrated similar outcomes between metformin and insulin-treated women with the exception of less neonatal hypoglycemia and slightly earlier gestational age at birth in the metformin group.
  • As metformin crosses the placenta, physicians need to learn more about the effect of exposure in utero to the child and adolescent.

Buschur E et al. Curr Diab Rep 2015; 15: 4. doi: 10.1007/s11892-014-0570-5

Gestational diabetes mellitus and postpartum care practices of nurse-midwives

By means of a survey of certified nurse-midwives, this study aimed to estimate the prevalence of postpartum diabetes screening and lifestyle modification counseling for women with a recent history of gestational diabetes.

Summary points
  • This study assessed the screening and counseling that Ohio certified nurse-midwives (CNMs) provide for postpartum women who have had gestational diabetes mellitus (GDM).
  • Only half of responding CNMs reported screening their postpartum patients for glucose tolerance after a GDM pregnancy.
  • Among CNMs who screen postpartum, only half reported using one of the recommended postpartum glucose tolerance tests.
  • About two-thirds of CNMs counseled women with recent histories of GDM to exercise regularly; however, only one-quarter of CNMs referred overweight or obese women with recent GDM histories to diet support groups or other nutrition counseling.
  • Midwives need to consistently screen postpartum women who have had a GDM pregnancy for glucose tolerance using either a fasting blood sugar or a 2-hour oral glucose test and to encourage these women to exercise regularly and lose weight if they are overweight or obese.

Ko JY et al. J Midwifery Women's Health 2013; 58: 33–40. doi: 10.1111/j.1542-2011.2012.00261.x