Glycemic targets in pregnancies affected by diabetes: historical perspective and future directions

Neurodevelopmental Programming of Adiposity: Contributions to Obesity Risk

This review analyzes the published evidence regarding maternal factors that influence the developmental programming of long-term adiposity in humans and animals via the central nervous system (CNS). We describe the physiological outcomes of perinatal underfeeding and overfeeding and explore potential mechanisms that may mediate the impact of such exposures on the development of feeding circuits within the CNS-including the influences of metabolic hormones and epigenetic changes. The perinatal environment, reflective of maternal nutritional status, contributes to the programming of offspring adiposity. The in utero and early postnatal periods represent critically sensitive developmental windows during which the hormonal and metabolic milieu affects the maturation of the hypothalamus. Maternal hyperglycemia is associated with increased transfer of glucose to the fetus driving fetal hyperinsulinemia. Elevated fetal insulin causes increased adiposity and consequently higher fetal circulating leptin concentration. Mechanistic studies in animal models indicate important roles of leptin and insulin in central and peripheral programming of adiposity, and suggest that optimal concentrations of these hormones are critical during early life. Additionally, the environmental milieu during development may be conveyed to progeny through epigenetic marks and these can potentially be vertically transmitted to subsequent generations. Thus, nutritional and metabolic/endocrine signals during perinatal development can have lifelong (and possibly multigenerational) impacts on offspring body weight regulation.

Glycemic control and neonatal outcomes in twin pregnancies with gestational diabetes mellitus

BACKGROUND

Preliminary data suggest that strict glycemic control in twin pregnancies with gestational diabetes mellitus may not improve outcomes but might increase the risk of fetal growth restriction.

OBJECTIVE

This study aimed to investigate the association of maternal glycemic control with the risk of gestational diabetes mellitus-related complications and small for gestational age in twin pregnancies complicated by gestational diabetes mellitus.

STUDY DESIGN

This was a retrospective cohort study of all patients with a twin pregnancy complicated by gestational diabetes mellitus in a single tertiary center between 2011 and 2020, and a matched control group of patients with a twin pregnancy without gestational diabetes mellitus in a 1:3 ratio. The exposure was the level of glycemic control, described as the proportion of fasting, postprandial, and overall glucose values within target. Good glycemic control was defined as a proportion of values within target above the 50th percentile. The first coprimary outcome was a composite variable of neonatal morbidity, defined as at least 1 of the following: birthweight >90th centile for gestational age, hypoglycemia requiring treatment, jaundice requiring phototherapy, birth trauma, or admission to the neonatal intensive care unit at term. A second coprimary outcome was small for gestational age, defined as birthweight <10th centile or <3rd centile for gestational age. Associations between the level of glycemic control and the study outcomes were estimated using logistic regression analysis and were expressed as adjusted odds ratio with 95% confidence interval.

RESULTS

A total of 105 patients with gestational diabetes mellitus in a twin pregnancy met the study criteria. The overall rate of the primary outcome was 32.4% (34/105), and the overall proportion of pregnancies with a small for gestational age newborn at birth was 43.8% (46/105). Good glycemic control was not associated with a reduction in the risk of composite neonatal morbidity when compared with suboptimal glycemic control (32.1% vs 32.7%; adjusted odds ratio, 2.06 [95% confidence interval, 0.77-5.49]). However, good glycemic control was associated with higher odds of small for gestational age compared with nongestational diabetes mellitus pregnancies, especially in the subgroup of diet-treated gestational diabetes mellitus (65.5% vs 34.0%, respectively; adjusted odds ratio, 4.17 [95% confidence interval, 1.74-10.01] for small for gestational age <10th centile; and 24.1% vs 7.0%, respectively; adjusted odds ratio, 3.97 [95% confidence interval, 1.42-11.10] for small for gestational age <3rd centile). In contrast, the rate of small for gestational age in gestational diabetes mellitus pregnancies with suboptimal control was not considerably different when compared with non-gestational diabetes mellitus pregnancies. In addition, in cases of diet-treated gestational diabetes mellitus, good glycemic control was associated with a left-shift of the distribution of birthweight centiles, whereas the distribution of birthweight centiles among gestational diabetes mellitus pregnancies with suboptimal control was similar to that of nongestational diabetes mellitus pregnancies.

CONCLUSION

In patients with gestational diabetes mellitus in a twin pregnancy, good glycemic control is not associated with a reduction in the risk of gestational diabetes mellitus-related complications but may increase the risk of a small for gestational age newborn in the subgroup of patients with mild (diet-treated) gestational diabetes mellitus. These findings further question whether the gestational diabetes mellitus glycemic targets used in singleton pregnancies also apply to twin pregnancies and support the concern that applying the same diagnostic criteria and glycemic targets in twin pregnancies may result in overdiagnosis and overtreatment of gestational diabetes mellitus and potential neonatal harm.

Different intensities of glycaemic control for women with gestational diabetes mellitus

BACKGROUND

Gestational diabetes mellitus (GDM) has major short- and long-term implications for both the mother and her baby. GDM is defined as a carbohydrate intolerance resulting in hyperglycaemia or any degree of glucose intolerance with onset or first recognition during pregnancy from 24 weeks' gestation onwards and which resolves following the birth of the baby. Rates for GDM can be as high as 25% depending on the population and diagnostic criteria used, and overall rates are increasing globally. There is wide variation internationally in glycaemic treatment target recommendations for women with GDM that are based on consensus rather than high-quality trials.

OBJECTIVES

To assess the effect of different intensities of glycaemic control in pregnant women with GDM on maternal and infant health outcomes.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform (26 September 2022), and reference lists of the retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs), cluster-RCTs, and quasi-RCTs. Trials were eligible for inclusion if women were diagnosed with GDM during pregnancy and the trial compared tighter and less-tight glycaemic targets during management. We defined tighter glycaemic targets as lower numerical glycaemic concentrations, and less-tight glycaemic targets as higher numerical glycaemic concentrations.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods for carrying out data collection, assessing risk of bias, and analysing results. Two review authors independently assessed trial eligibility for inclusion, evaluated risk of bias, and extracted data for the four included studies. We assessed the certainty of evidence for selected outcomes using the GRADE approach. Primary maternal outcomes included hypertensive disorders of pregnancy and subsequent development of type 2 diabetes. Primary infant outcomes included perinatal mortality, large-for-gestational-age, composite of mortality or serious morbidity, and neurosensory disability.

MAIN RESULTS

This was an update of a previous review completed in 2016. We included four RCTs (reporting on 1731 women) that compared a tighter glycaemic control with less-tight glycaemic control in women diagnosed with GDM. Three studies were parallel RCTs, and one study was a stepped-wedged cluster-RCT. The trials took place in Canada, New Zealand, Russia, and the USA. We judged the overall risk of bias to be unclear. Two trials were only published in abstract form. Tight glycaemic targets used in the trials ranged between ≤ 5.0 and 5.1 mmol/L for fasting plasma glucose and ≤ 6.7 and 7.4 mmol/L postprandial. Less-tight targets for glycaemic control used in the included trials ranged between < 5.3 and 5.8 mmol/L for fasting plasma glucose and < 7.8 and 8.0 mmol/L postprandial. For the maternal outcomes, compared with less-tight glycaemic control, the evidence suggests a possible increase in hypertensive disorders of pregnancy with tighter glycaemic control (risk ratio (RR) 1.16, 95% confidence interval (CI) 0.80 to 1.69, 2 trials, 1491 women; low certainty evidence); however, the 95% CI is compatible with a wide range of effects that encompass both benefit and harm. Tighter glycaemic control likely results in little to no difference in caesarean section rates (RR 0.98, 95% CI 0.82 to 1.17, 3 studies, 1662 women; moderate certainty evidence) or induction of labour rates (RR 0.96, 95% CI 0.78 to 1.18, 1 study, 1096 women; moderate certainty evidence) compared with less-tight control. No data were reported for the outcomes of subsequent development of type 2 diabetes, perineal trauma, return to pre-pregnancy weight, and postnatal depression. For the infant outcomes, it was difficult to determine if there was a difference in perinatal mortality (RR not estimable, 2 studies, 1499 infants; low certainty evidence), and there was likely no difference in being large-for-gestational-age (RR 0.96, 95% CI 0.72 to 1.29, 3 studies, 1556 infants; moderate certainty evidence). The evidence suggests a possible reduction in the composite of mortality or serious morbidity with tighter glycaemic control (RR 0.84, 95% CI 0.55 to 1.29, 3 trials, 1559 infants; low certainty evidence); however, the 95% CI is compatible with a wide range of effects that encompass both benefit and harm. There is probably little difference between groups in infant hypoglycaemia (RR 0.92, 95% CI 0.72 to 1.18, 3 studies, 1556 infants; moderate certainty evidence). Tighter glycaemic control may not reduce adiposity in infants of women with GDM compared with less-tight control (mean difference -0.62%, 95% CI -3.23 to 1.99, 1 study, 60 infants; low certainty evidence), but the wide CI suggests significant uncertainty. We found no data for the long-term outcomes of diabetes or neurosensory disability. Women assigned to tighter glycaemic control experienced an increase in the use of pharmacological therapy compared with women assigned to less-tight glycaemic control (RR 1.37, 95% CI 1.17 to 1.59, 4 trials, 1718 women). Tighter glycaemic control reducedadherence with treatment compared with less-tight glycaemic control (RR 0.41, 95% CI 0.32 to 0.51, 1 trial, 395 women). Overall the certainty of evidence assessed using GRADE ranged from low to moderate, downgraded primarily due to risk of bias and imprecision.

AUTHORS' CONCLUSIONS

This review is based on four trials (1731 women) with an overall unclear risk of bias. The trials provided data on most primary outcomes and suggest that tighter glycaemic control may increase the risk of hypertensive disorders of pregnancy. The risk of birth of a large-for-gestational-age infant and perinatal mortality may be similar between groups, and tighter glycaemic targets may result in a possible reduction in composite of death or severe infant morbidity. However, the CIs for these outcomes are wide, suggesting both benefit and harm. There remains limited evidence regarding the benefit of different glycaemic targets for women with GDM to minimise adverse effects on maternal and infant health. Glycaemic target recommendations from international professional organisations vary widely and are currently reliant on consensus given the lack of high-certainty evidence. Further high-quality trials are needed, and these should assess both short- and long-term health outcomes for women and their babies; include women's experiences; and assess health services costs in order to confirm the current findings. Two trials are ongoing.

Re-examination of the estimated average requirement for carbohydrate intake during pregnancy: Addition of placental glucose consumption

Evidence-based dietary reference intakes for nutrients in healthy individuals were last set in 2005 by the Institute of Medicine. For the first time, these recommendations included a guideline for carbohydrate intake during pregnancy. The recommended dietary allowance (RDA) was set at ≥175 g/d or 45%-65% of total energy intake. In the decades since, carbohydrate intake has been declining in some populations, and many pregnant women consume carbohydrates below the RDA. The RDA was developed to account for both maternal brain and fetal brain glucose requirements. However, the placenta also requires glucose as its dominant energy substrate and is as dependent on maternal glucose as the brain. Prompted by the availability of evidence demonstrating the rate and quantity of human placental glucose consumption, we calculated a potential new estimated average requirement (EAR) for carbohydrate intake to account for placental glucose consumption. Further, by narrative review, we have re-examined the original RDA by applying contemporary measurements of adult brain and whole-body fetal glucose consumption. We also propose, using physiologic rationale, that placental glucose consumption be included in pregnancy nutrition considerations. Calculated from human in vivo placental glucose consumption data, we suggest that 36 g/d represents an EAR for adequate glucose to support placental metabolism without supplementation by other fuels. A potential new EAR of 171 g/d accounts for maternal (100 g) and fetal (35 g) brain, and now placental glucose utilization (36 g), and with extrapolation to meet the needs of nearly all healthy pregnant women, would result in a modified RDA of 220 g/d. Lower and upper safety thresholds for carbohydrate intake remain to be determined, of importance as preexisting and gestational diabetes continue to rise globally, and nutrition therapy remains the cornerstone of treatment.

A Clinical Update on Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) traditionally refers to abnormal glucose tolerance with onset or first recognition during pregnancy. GDM has long been associated with obstetric and neonatal complications primarily relating to higher infant birthweight and is increasingly recognized as a risk factor for future maternal and offspring cardiometabolic disease. The prevalence of GDM continues to rise internationally due to epidemiological factors including the increase in background rates of obesity in women of reproductive age and rising maternal age and the implementation of the revised International Association of the Diabetes and Pregnancy Study Groups' criteria and diagnostic procedures for GDM. The current lack of international consensus for the diagnosis of GDM reflects its complex historical evolution and pragmatic antenatal resource considerations given GDM is now 1 of the most common complications of pregnancy. Regardless, the contemporary clinical approach to GDM should be informed not only by its short-term complications but also by its longer term prognosis. Recent data demonstrate the effect of early in utero exposure to maternal hyperglycemia, with evidence for fetal overgrowth present prior to the traditional diagnosis of GDM from 24 weeks' gestation, as well as the durable adverse impact of maternal hyperglycemia on child and adolescent metabolism. The major contribution of GDM to the global epidemic of intergenerational cardiometabolic disease highlights the importance of identifying GDM as an early risk factor for type 2 diabetes and cardiovascular disease, broadening the prevailing clinical approach to address longer term maternal and offspring complications following a diagnosis of GDM.

Perceptions of Key Informant Health Professionals before implementing tighter glycaemic targets for women with gestational diabetes mellitus in New Zealand

Background

Tighter glycaemic targets may be of benefit for women with GDM and their infants. Barrier and enabler identification prior to implementation of tighter glycaemic targets for women with GDM may support a successful transition.

Methods

A cross-sectional questionnaire survey was conducted among Key Informant Health Professionals in ten hospitals in New Zealand. The survey assessed what was currently working using less tight glycaemic targets; what barriers and enablers were considered likely when introducing tighter glycaemic targets and whether these perceptions differed by health professional groups.

Results

Sixty Key Health Informant Health Professionals completed the survey. When using the lower glycaemic targets, participants considered that women with GDM found the targets easy to use and that collaborative collegial support was effective. No significant barriers were identified. Perceived enablers identified prior to implementation of tighter targets included receiving collegial support (40, 67%), attending education sessions (38, 63%), use of pocket prompt cards (31, 52%), availability of wall charts (25, 42%) and glycaemic target reminder stickers (24, 40%). For health professionals referring into the Diabetes in Pregnancy Service effective communication (50, 83%) was considered important. Perceived barriers were confusion over glycaemic targets use (27 (45%), not being informed of the glycaemic target change (31, 52%), non-involvement with multidisciplinary decisions (29, 48%) and increased difficulty of blood glucose control for women (48, 80%). Overall, barriers and enablers between Health Professional groups did not differ.

Discussion

Key Informant Health Professionals reported effective communication as a key perceived enabler and that woman would find it more difficult to control their blood glucose concentrations. Education sessions, multidisciplinary engagement, wall charts and stickers were considered effective to overcome the perceived barriers. Further research is needed to assess if the barriers perceived were realised and if the perceived enablers supported the implementation of the tighter glycaemic targets effectively.

The importance of nutrition in pregnancy and lactation: lifelong consequences

Most women in the United States do not meet the recommendations for healthful nutrition and weight before and during pregnancy. Women and providers often ask what a healthy diet for a pregnant woman should look like. The message should be “eat better, not more.” This can be achieved by basing diet on a variety of nutrient-dense, whole foods, including fruits, vegetables, legumes, whole grains, healthy fats with omega-3 fatty acids that include nuts and seeds, and fish, in place of poorer quality highly processed foods. Such a diet embodies nutritional density and is less likely to be accompanied by excessive energy intake than the standard American diet consisting of increased intakes of processed foods, fatty red meat, and sweetened foods and beverages. Women who report “prudent” or “health-conscious” eating patterns before and/or during pregnancy may have fewer pregnancy complications and adverse child health outcomes. Comprehensive nutritional supplementation (multiple micronutrients plus balanced protein energy) among women with inadequate nutrition has been associated with improved birth outcomes, including decreased rates of low birthweight. A diet that severely restricts any macronutrient class should be avoided, specifically the ketogenic diet that lacks carbohydrates, the Paleo diet because of dairy restriction, and any diet characterized by excess saturated fats. User-friendly tools to facilitate a quick evaluation of dietary patterns with clear guidance on how to address dietary inadequacies and embedded support from trained healthcare providers are urgently needed.

Recent evidence has shown that although excessive gestational weight gain predicts adverse perinatal outcomes among women with normal weight, the degree of prepregnancy obesity predicts adverse perinatal outcomes to a greater degree than gestational weight gain among women with obesity. Furthermore, low body mass index and insufficient gestational weight gain are associated with poor perinatal outcomes. Observational data have shown that first-trimester gain is the strongest predictor of adverse outcomes. Interventions beginning in early pregnancy or preconception are needed to prevent downstream complications for mothers and their children. For neonates, human milk provides personalized nutrition and is associated with short- and long-term health benefits for infants and mothers. Eating a healthy diet is a way for lactating mothers to support optimal health for themselves and their infants.

Glycemic profile of women with normoglycemia and gestational diabetes mellitus during early pregnancy using continuous glucose monitoring system

AIM

We studied women between 8 and 20 weeks of gestation with the aim of evaluating and comparing those having normoglycemia and GDM according to WHO 2013 criteria.

METHODS

In this cross-sectional study (2017-2019), eligible pregnant women underwent a 75-g OGTT, followed by placement of a CGMS.

RESULTS

Women (n = 96, 58 with normoglycemia and 38 with GDM) were enrolled at 14.0 ± 3.2 weeks of gestation. Mean preprandial, 1-h and 2-h postprandial and peak glucose values were significantly higher in women with GDM. Peak glucose value was achieved 60.0 ± 12.3 and 64.3 ± 11.6 min after meal in the normoglycemia and GDM group, respectively. 24-h mean glucose (5.8 ± 0.6 vs. 5.3 ± 0.4 mmol/L), mean daytime glucose (6.0 ± 0.6 vs. 5.5 ± 0.4 mmol/L) and mean nocturnal glucose (5.4 ± 0.7 vs. 5.0 0 ± 0.5 mmol/L) were significantly higher in women with GDM. Total time spent in range was significantly lower in the GDM group compared to the normoglycemia group (92.1 vs. 98.2%).

CONCLUSIONS

This study highlights differences in glycemic patterns between women with normoglycemia and GDM in the context of a South Asian population where burden of GDM is high but good quality data in early pregnancy are limited.

Low-Carbohydrate Diets for Gestational Diabetes

Nutrition therapy provides the foundation for treatment of gestational diabetes (GDM), and has historically been based on restricting carbohydrate (CHO) intake. In this paper, randomized controlled trials (RCTs) are reviewed to assess the effects of both low- and higher CHO nutrition approaches in GDM. The prevailing pattern across the evidence underscores that although CHO restriction improves glycemia at least in the short-term, similar outcomes could be achievable using less restrictive approaches that may not exacerbate IR. The quality of existing studies is limited, in part due to dietary non-adherence and confounding effects of treatment with insulin or oral medication. Recent evidence suggests that modified nutritional manipulation in GDM from usual intake, including but not limited to CHO restriction, improves maternal glucose and lowers infant birthweight. This creates a platform for future studies to further clarify the impact of multiple nutritional patterns in GDM on both maternal and infant outcomes.

Good glycemic control of gestational diabetes mellitus is associated with the attenuation of future maternal cardiovascular risk: a retrospective cohort study

BACKGROUND

To examine whether glycemic control of gestational diabetes mellitus (GDM) could modify the risk for future maternal metabolic and cardiovascular morbidities.

METHODS

A retrospective cohort study of women with a first diagnosis of GDM who delivered between 1991 and 2011. Women were divided into groups of good and poor glycemic control, defined as a mean daily glucose of up to 95 mg/dL (N = 230) and more than 95 mg/dL (N = 216), respectively. In addition, a control group of women without GDM (N = 352) was also analyzed. The primary outcomes were the development of type 2 diabetes mellitus (T2DM), obesity, hypertension, or dyslipidemia.

RESULTS

Mean follow-up time was 15.8 ± 5.1 years. Assessment was performed at a maternal age of 45 ± 7 years. The rates of the study outcomes in the control, GDM with good glycemic control and GDM with poor glycemic control were as follows: T2DM [19 (5.4%), 87 (38%), 127 (57%)]; hypertension [44 (13%), 42 (18%), 44 (20%)]; obesity [111 (32%), 112 (48%), 129 (58%)]; and dyslipidemia [49 (14%), 67 (29%), 106 (48%)]. Glycemic control was an independent risk factor for T2DM in multivariate Cox regression analysis (hazard ratio (HR) for poor glycemic control vs. controls 10.7 95% CI [6.0-19.0], good glycemic control vs. control HR 6.0 [3.3-10.8], and poor glycemic control vs. good glycemic control HR 1.8 [1.3-2.4]). Glycemic control was also an independent risk factor for dyslipidemia (poor glycemic control vs. controls HR 3.7 [2.3-5.8], good glycemic control vs. controls HR 2.0 [1.2-3.2], and poor glycemic control vs. good glycemic control HR 1.8 1.8 [1.3-2.6]). The fasting glucose level during oral glucose tolerance test (OGTT) was also an independent risk factor for these complications. The interaction term between glycemic control and the fasting value of the OGTT was not statistically significant, suggesting that the effect of glycemic control on the rate of future T2DM and dyslipidemia was not modified by the baseline severity of GDM.

CONCLUSION

GDM and especially poor glycemic control are associated with T2DM and dyslipidemia. Strict glycemic control for reducing that risk should be evaluated in prospective trials.

Impact of different glycaemic treatment targets on pregnancy outcomes in gestational diabetes

AIM

With no current randomized trials, we explored the impact of tight compared with standard treatment targets on pregnancy outcomes in gestational diabetes mellitus (GDM).

METHODS

This cohort study of singleton births ≥ 28 weeks' gestation was conducted at two major Australian maternity services (2009-2013). Standardized maternal, neonatal and birth outcomes were examined using routine healthcare data and compared for women with GDM at Service One (n = 2885) and Service Two (n = 1887). Services applied different treatment targets: Service One (standard targets, reference group) fasting < 5.5 mmol/l, 2-h postprandial < 7.0 mmol/l; Service Two (tight targets) fasting < 5.0 mmol/l, 2-h postprandial < 6.7 mmol/l. Multivariable regression with propensity score adjustment was used to examine associations between targets and outcomes.

RESULTS

GDM prevalence and insulin use were 7.9% and 31% at Service One, and 5.7% and 46% at Service Two. There were no differences in primary outcomes: birthweight > 90th centile [adjusted odds ratio (OR) 1.06, 95% confidence interval (CI) 0.87-1.30] and < 10th centile (OR 0.84, 95% CI 0.70-1.01), or secondary outcomes gestational hypertension, pre-eclampsia, shoulder dystocia or a perinatal composite. Service Two with tight targets had increased induction of labour (OR 3.63, 95% CI 3.17-4.16), elective Caesarean section (OR 1.75, 95% CI 1.37-2.23) and Apgar scores < 7 at 5 min (OR 1.54, 95% CI 1.05-2.25), decreased hypoglycaemia (OR 0.76, 95% CI 0.61-0.94]), jaundice (OR 0.47, 95% CI 0.35-0.63) and respiratory distress (OR 0.68, 95% CI 0.47-0.98).

CONCLUSIONS

Tight GDM treatment targets were associated with greater insulin use and no difference in primary birthweight outcomes. The service with tight targets had higher obstetric intervention, lower rates of reported hypoglycaemia, jaundice, respiratory distress and lower Apgar scores. High-quality interventional data are required before tight treatment targets can be implemented.

The Utility of Lower Glycemic Targets for Treating Gestational Diabetes: A Retrospective Study

OBJECTIVE

In vivo study of glucose homeostasis in pregnancy suggests normal glucose levels are lower than current glycemic targets used in gestational diabetes. After the HAPO study results, our institution began using glycemic targets of fasting 85 mg/dL and 2-hour postprandial of 110 mg/dL. We reviewed our results.

METHODS

A retrospective cohort of GDM patients that delivered at KUMC from January 2007 to May 2017 was reviewed. All patients were diagnosed with the 2-step Carpenter-Coustan thresholds. High targets were compared with low targets. The primary outcome investigated was birthweight > 90% (large for gestational age, LGA).

RESULTS

604 patients were studied, and 34% were treated with low glycemic targets. Our unadjusted results showed that the low-target group had a lower incidence of LGA infants (24.0 vs. 31.8%), higher incidence of neonatal hypoglycemia (20.7 vs. 11.6%), and inductions (39.4 vs. 20.5%). After adjustment for demographic variables, only a higher risk of inductions remained (aOR 2.54 (1.44, 4.49)).

CONCLUSION

Lower glycemic targets did not produce large reductions in fetal overgrowth, but they were associated with a higher rate of inductions. As there were no observed differences in maternal or neonatal outcomes otherwise, aiming for lower glycemic targets in GDM is likely not cost-effective.

Developmental Programming of Obesity and Diabetes in Mouse, Monkey, and Man in 2018: Where Are We Headed?

Childhood obesity and its comorbidities continue to accelerate across the globe. Two-thirds of pregnant women are obese/overweight, as are 20% of preschoolers. Gestational diabetes mellitus (GDM) is escalating, affecting up to 1 in 5 pregnant women. The field of developmental origins of health and disease has begun to move beyond associations to potential causal mechanisms for developmental programming. Evidence across species compellingly demonstrates that maternal obesity, diabetes, and Western-style diets create a long-lasting signature on multiple systems, including infant stem cells, the early immune system, and gut microbiota. Such exposures accelerate adipogenesis, disrupt mitochondrial metabolism, and impair energy sensing, affecting neurodevelopment, liver, pancreas, and skeletal muscle. Attempts to prevent developmental programming have met with very limited success. A challenging level of complexity is involved in how the host genome, metabolome, and microbiome throughout pregnancy and lactation increase the offspring's risk of metabolic diseases across the life span. Considerable gaps in knowledge include the timing of exposure(s) and permanence or plasticity of the response, encompassing effects from both maternal and paternal dysmetabolism. Basic, translational, and human intervention studies targeting pathways that connect diet, microbiota, and metabolism in mothers with obesity/GDM and their infants are a critical unmet need and present new challenges for disease prevention in the next generation.

Nutrition therapy within and beyond gestational diabetes

With the global rising prevalence of gestational diabetes (GDM), an adaptable, economical approach to nutrition therapy that effectively controls maternal glycemia while promoting normal fetal growth will have far-reaching implications. The conventional focus has been to rigidly limit all types of carbohydrate. While controlling glucose, this approach fosters maternal anxiety and is a primary barrier to adherence. Many mothers substitute fat for carbohydrate, which may unintentionally enhance lipolysis, promote elevated free fatty acids (FFA), and worsen maternal insulin resistance (IR). Nutrition that worsens IR may facilitate nutrient shunting across the placenta, promoting excess fetal fat accretion. Evidence suggests that liberalizing higher quality, nutrient-dense carbohydrates results in controlled fasting/postprandial glucose, lower FFA, improved insulin action, vascular benefits, and may reduce excess infant adiposity. Thus, a less carbohydrate-restricted approach may improve maternal adherence when combined with higher quality carbohydrates, lower fat, appropriate caloric intake, and ethnically acceptable foods. Such a diet can be culturally sensitive, socioeconomically attentive, minimize further weight gain in GDM, with potential relevance for pregnancies complicated by overweight/obesity. Future research is needed to better understand the effect of macronutrient composition on the placenta and gut microbiome, the benefits/risks of nonnutritive sweeteners, and whether precision-nutrition is beneficial in pregnancy.

Maternal Lipids and Fetal Overgrowth: Making Fat from Fat

There is increasing recognition that maternal glucose concentrations lower than those previously used for diagnosis of gestational diabetes mellitus (GDM) and targeted for treatment can result in excess fetal growth. Yet, mothers with GDM who appear to have optimal glycemic control and mothers with obesity and normal glucose tolerance still have a significantly increased risk for delivering infants who are large for gestational age, or even more importantly, who have increased adiposity at birth. What is less appreciated is that in addition to glucose, maternal lipids are also substrates for fetal fat accretion and that placental lipases can hydrolyze maternal triglycerides (TGs) to free fatty acids for fetal-placental availability. Maternal TG levels are 40% to 50% higher on average in mothers with obesity and GDM compared to those in normal-weight mothers early in pregnancy and are sustained at higher levels throughout gestation. Increasing evidence supports that maternal TG, both fasting and postprandial, are also predictors of newborn adiposity (newborn %fat), a risk factor for childhood obesity, and that early exposure is at least as strong of a risk factor as later exposure in mothers with obesity. In the setting of maternal nutrient excess and maternal insulin resistance, which lead to fetal hyperinsulinemia, excess free fatty acid exposure in the fetus may result in lipid storage and fetal fat development in subcutaneous and possibly other depots. In this commentary, we provide further evidence to make a case for targeting maternal fasting and postprandial TG in mothers with obesity who have elevated TG in early pregnancy to determine whether a TG-lowering interventional approach might limit fetal overgrowth and potentially mitigate the intrauterine contribution to childhood obesity and metabolic disease.

Glucose Targets and Insulin Choice in Pregnancy: What Has Changed in the Last Decade?

PURPOSE OF REVIEW

To review current glycaemic targets and the potential use of newer insulin formulations in pregnancy.

RECENT FINDINGS

The impact of stricter glycaemic control on perinatal outcomes remains controversial, showing conflicting results. Current ongoing randomised trials investigating the role of tighter glucose targets in pregnancy should help clarify the benefit of tighter glucose control. Optimal timing for self-monitoring blood glucose (SMBG) remains debatable. Data suggest that post-prandial SMBG, particularly at 1 h, offers the best prediction of adverse perinatal outcome. To achieve these targets, insulin is the standard therapy. Novel insulin formulations offer benefits outside of pregnancy. Recent data on the use of new insulins in pregnancy (e.g. insulin degludec and glargine (U 300)) is limited to case reports. Glycaemic targets have remained unchanged in the last decade. Studies using stricter glycaemic targets may improve perinatal outcomes. Newer insulin formulations may offer increased flexibility and glycaemic control. Clinicians caring for women with diabetes striving to minimise adverse perinatal outcomes will find this review of interest.

Maternal Non-glycemic Contributors to Fetal Growth in Obesity and Gestational Diabetes: Spotlight on Lipids

PURPOSE OF REVIEW

Excess fetal growth is increasingly recognized as a risk factor for childhood obesity, and mounting evidence supports that maternal glucose is not the only driver. This review focuses on the role of clinically applicable maternal non-glycemic contributors to excess fetal growth, particularly lipids, in addition to amino acids (AA), insulin resistance, inflammation, maternal nutrition, and gestational weight gain (GWG) in obesity and gestational diabetes mellitus (GDM).

RECENT FINDINGS

Lipids, specifically triglycerides and free fatty acids, appear to be strong contributors to excess fetal fat accretion and adiposity at birth, particularly in obese pregnancies, which account for the largest number of large-for-gestational-age infants. Maternal pre-pregnancy body mass index (BMI), GWG, insulin resistance, inflammation, and glucose, lipid, and AA concentrations have both independent and interacting effects on fetal growth, operating both early and late in pregnancy. All are sensitive to maternal nutrition. Early vs. later gestational exposure to excess maternal fuels in fasting and postprandial conditions may differentially impact fetoplacental outcomes. Compelling evidence suggests that targeting interventions early in pregnancy beyond glucose may be critical to improve fetal growth patterns.

Carbohydrate Content in the GDM Diet: Two Views: View 1: Nutrition Therapy in Gestational Diabetes: The Case for Complex Carbohydrates

IN BRIEF Restriction of dietary carbohydrate has been the cornerstone for treatment of gestational diabetes mellitus (GDM). However, there is evidence that a balanced liberalization of complex carbohydrate as part of an overall eating plan in GDM meets treatment goals and may mitigate maternal adipose tissue insulin resistance, both of which may promote optimal metabolic outcomes for mother and offspring.

Different intensities of glycaemic control for women with gestational diabetes mellitus

BACKGROUND

Gestational diabetes mellitus (GDM) has major short- and long-term implications for both the mother and her baby. GDM is defined as a carbohydrate intolerance resulting in hyperglycaemia or any degree of glucose intolerance with onset or first recognition during pregnancy from 24 weeks' gestation onwards and which resolves following the birth of the baby. Rates for GDM can be as high as 25% depending on the population and diagnostic criteria used and rates are increasing globally. Risk factors associated with GDM include advanced maternal age, obesity, ethnicity, family history of diabetes, and a previous history of GDM, macrosomia or unexplained stillbirth. There is wide variation internationally in glycaemic treatment target recommendations for women with GDM that are based on consensus rather than high-quality trials.

OBJECTIVES

To assess the effect of different intensities of glycaemic control in pregnant women with GDM on maternal and infant health outcomes.

SEARCH METHODS

We searched the Cochrane Pregancy and Childbirth Group's Trials Register (31 January 2016), ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (1 February 2016) and reference lists of the retrieved studies.

SELECTION CRITERIA

We included one randomised controlled trial. Cluster-randomised and quasi-randomised controlled trials were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

We used the methods described in the Cochrane Handbook for Systematic Reviews of Interventions for carrying out data collection, assessing study quality and analysing results. Two review authors independently assessed trial eligibility for inclusion, evaluated methodological quality and extracted data for the one included study. We sought additional information from one trial author but had no response. We assessed the quality of evidence for selected outcomes using the GRADE approach.

MAIN RESULTS

We included one Canadian trial of 180 women, recruited between 20 to 32 weeks' gestation, who had been diagnosed with GDM. Data from 171 of the 180 women were published as a conference abstract and no full report has been identified. The overall risk of bias of the single included study was judged to be unclear.The included trial did not report on any of this review's primary outcomes. For the mother, these were hypertension disorders of pregnancy or subsequent development of type 2 diabetes. For the infant, our primary outcomes were (perinatal (fetal and neonatal) mortality; large-for-gestational age; composite of death or severe morbidity or later childhood neurosensory disability).The trial did report data relating to some of this review's secondary outcomes. There was no clear difference in caesarean section rates for women assigned to using strict glycaemic targets (pre-prandial 5.0 mmol/L (90 mg/L) and at one-hour postprandial 6.7 mmol/L (120 mg/dL)) (28/85, 33%) when compared with women assigned to using liberal glycaemic targets (pre-prandial 5.8 mmol/L (103 mg/dL) and at one-hour postprandial 7.8 mmol/L (140 mg/dL)) (21/86, 24%) (risk ratio (RR) 1.35, 95% confidence interval (CI) 0.83 to 2.18, one trial, 171 women; very low quality). Using the GRADE approach, we found the quality of the evidence to bevery low for caesarean section due to poor reporting of risk of bias, imprecision and publication bias. Strict glycaemic targets were associated with an increase in the use of pharmacological therapy (identified as the use of insulin in this study) (33/85; 39%) compared with liberal glycaemic targets (18/86; 21%) (RR 1.85, 95% CI 1.14 to 3.03; one trial, 171 women). CIs are wide suggesting imprecision and caution is required when interpreting the data. No other secondary maternal outcome data relevant to this review were reported. For the infant, there were no clear differences between the groups of women receiving strict and liberal glycaemic targets for macrosomia (birthweight greater than 4000 g) (RR 1.35, 95% CI 0.31 to 5.85, one trial, 171 babies); small-for-gestational age (RR 1.12, 95% CI 0.48 to 2.63, one trial, 171 babies); birthweight (mean difference (MD) -92.00 g, 95% CI -241.97 to 57.97, one trial, 171 babies) or gestational age (MD -0.30 weeks, 95% CI -0.73 to 0.13, one trial, 171 babies). Adverse effects data were not reported. No other secondary neonatal outcomes relevant to this review were reported.

AUTHORS' CONCLUSIONS

This review is based on a single study (involving 180 women) with an unclear risk of bias. The trial (which was only reported in a conference abstract) did not provide data for any of this review's primary outcomes but did provide data for a limited number of our secondary outcomes. There is insufficient evidence to guide clinical practice for targets for glycaemic control for women with GDM to minimise adverse effects on maternal and fetal health. Glycaemic target recommendations from international professional organisations for maternal glycaemic control vary widely and are reliant on consensus given the lack of high-quality evidence.Further high-quality trials are needed, and these should compare different glycaemic targets for guiding treatment of women with GDM, assess both short-term and long-term health outcomes for women and their babies, include women's experiences and assess health services costs. Four studies are ongoing.

Pregnancy Reveals Evolving Risk for Cardiometabolic Disease in Women

Pregnancy serves as a cardiometabolic stressor that may unmask underlying metabolic and vascular abnormalities in an evolving continuum of pathophysiology. In 2011, the American Heart Association indicated that a diagnosis of pre-eclampsia, gestational hypertension, or gestational diabetes classified a woman as at risk for cardiovascular disease. In this article, we discuss hypertensive disorders of pregnancy, gestational diabetes, and preterm birth as risk factors for future cardiovascular disease in women.