Metformin should be considered in the treatment of gestational diabetes: a prospective randomised study

Metformin in the management of diabetes during pregnancy and lactation

This review explores the current place of metformin in the management of gestational diabetes (GDM) and type 2 diabetes during pregnancy and lactation. The rationale and basic pharmacology of metformin usage in pregnancy is discussed along with the evidence from observational and randomized controlled trials in women with GDM or overt diabetes. There seems to be adequate evidence of efficacy and short-term safety of metformin in relation to maternal and neonatal outcomes in GDM, with possible benefits related to lower maternal weight gain and lower risk of neonatal hypoglycemia and macrosomia. Additionally, metformin offers the advantages of oral administration, convenience, less cost and greater acceptability. Metformin may, therefore, be considered in milder forms of GDM where glycemic goals are not attained by lifestyle modification. However, failure rate is likely to be higher in those with an earlier diagnosis of GDM, higher blood glucose, higher body mass index (BMI) or previous history of GDM, and insulin remains the cornerstone of pharmacological treatment in such cases. The use of metformin in type 2 diabetes has been assessed in observational and small randomized trials. Metformin monotherapy in women with overt diabetes is highly unlikely to achieve glycemic targets. Hence, the use should be restricted as adjunct to insulin and may be considered in women with high insulin dose requirements or rapid weight gain. There is clearly a need for more clinical trials to assess the effect of combined insulin plus metformin therapy in pregnancy with type 2 diabetes. Additionally, there is a paucity of data on long-term effects in offspring exposed to metformin in utero. It is imperative to further explore its impact on offspring as metformin has significant transplacental transfer and has the potential to impact the programming of the epigenome. Therefore, caution must be exercised when prescribing metformin in pregnant women. More research is clearly needed before metformin can be considered as standard of care in the management of diabetes during pregnancy.

Insulin therapy and its consequences for the mother, foetus, and newborn in gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is a disease characterised by glucose intolerance and first diagnosed in pregnancy. This condition relates to an anomalous placental environment and aberrant placental vascular function. GDM-associated hyperglycaemia changes the placenta structure leading to abnormal development and functionality of this vital organ. Aiming to avoid the GDM-hyperglycaemia and its deleterious consequences in the mother, the foetus and newborn, women with GDM are firstly treated with a controlled diet therapy; however, some of the women fail to reach the recommended glycaemia values and therefore they are passed to the second line of treatment, i.e., insulin therapy. The several protocols available in the literature regarding insulin therapy are variable and not a clear consensus is yet reached. Insulin therapy restores maternal glycaemia, but this beneficial effect is not reflected in the foetus and newborn metabolism, suggesting that other factors than d-glucose may be involved in the pathophysiology of GDM. Worryingly, insulin therapy may cause alterations in the placenta and umbilical vessels as well as the foetus and newborn additional to those seen in pregnant women with GDM treated with diet. In this review, we summarised the variable information regarding indications and protocols for administration of the insulin therapy and the possible outcomes on the function and structure of the foetoplacental unit and the neonate parameters from women with GDM.

Intrauterine exposure to metformin: Evaluation of endothelial and perivascular adipose tissue function in abdominal aorta of adult offspring

The biguanide metformin (MET) has been used during pregnancy for treatment of polycystic ovary syndrome and gestational diabetes. MET crosses the placenta and maternal treatment can expose the progeny to this drug during important phases of body development. Direct vascular protective effects have been described with the treatment of metformin. Nevertheless, it is unclear whether intrauterine exposure to metformin is safe for the vascular system of offspring. Thus, the present study aimed to investigate the intrinsic effects of metformin exposure in utero in the offspring abdominal aorta reactivity, in the presence and absence of perivascular adipose tissue (PVAT) and endothelium. For this, Wistar rats were treated with metformin 293 mg/kg/day (MET) or water (CTR) by gavage during the gestational period. The abdominal aorta reactivity to phenylephrine, acetylcholine, and sodium nitroprusside was evaluated in male adult offspring. It was observed that abdominal aorta relaxation was similar between MET and CTR groups in the presence or absence of PVAT. In addition, the contraction to phenylephrine was similar between MET and CTR groups in the presence and absence of PVAT and endothelium. Therefore, metformin exposure during pregnancy had no intrinsic effect on the offspring abdominal aorta PVAT and endothelial function, demonstrating it to be safe to the vascular system of the offspring.

Maternal and Neonatal Outcomes in Pregnant Women with Gestational Diabetes Mellitus Treated with Diet, Metformin or Insulin

AIM:

Aim of the study was to compare outcomes of pregnancy in gestational diabetes mellitus (GDM) treated with metformin, insulin, or diet.

MATERIAL AND METHODS:

The study included 48 women with GDM treated with metformin, 101 with insulin, and 200 women on a diet from the Outpatient Department of Endocrinology and University Clinic of Obstetrics and Gynecology in Skopje.

RESULTS:

The groups were comparable in age, smoking cigarettes and positive family history of diabetes. Mean glycosylated haemoglobin (HbA1c) at 37 gestation week, mean fasting, postprandial glycaemia, and gestational age at delivery were lower in diet and metformin than insulin group. No differences in mode of delivery were observed between the metformin and insulin group. Women in metformin group had a significantly lower incidence of LGA newborns than diet and insulin groups. The percent of SGA new-borns was higher in insulin group than diet and metformin groups. The incidence of neonatal hypoglycemia was statistically significantly higher in the insulin group than in the metformin and diet group.

CONCLUSION:

Metformin in women with GDM can improve maternal and neonatal outcomes compared with those treated with diet or insulin.

Pharmacological treatment of gestational diabetes mellitus: point/counterpoint

Controversies persist over the most efficacious pharmacologic treatment for gestational diabetes mellitus. For purposes of accuracy in this article, the individual American College of Obstetricians and Gynecologists Practice Bulletin and American Diabetes Association Standards of Medical Care positions on each issue are quoted and then deliberated with evidence of counter claims presented in point/counterpoint. This is a review of all the relevant evidence for the most holistic picture possible. The main issues are (1) which diabetic drugs cross the placenta, (2) the quality of evidence and data source validity, (3) the rationale for the designation of glucose control as the primary outcome in gestational diabetes mellitus, and (4) which drugs (metformin, glyburide, or insulin) are most effective in improving secondary outcomes. The concept that 1 drug fits all, whether it be insulin, glyburide, or metformin, is a fallacy. Different drugs provide certain benefits but not all the benefits and not to all patients. In addition, the steps in the gestational diabetes mellitus management decision path and the current cost of the use of insulin, glyburide, or metformin are addressed. In the future, we must consider studying the potential of diabetic drugs that currently are used in nonpregnancy and incorporating the concept of precision medicine in the decision tree to maximize pregnancy outcomes.

Predictors of metformin failure in gestational diabetes mellitus (GDM)

INTRODUCTION AND OBJECTIVE

The role of metformin in gestational diabetes mellitus (GDM) is also increasing. However, almost half of metformin-treated women required additional insulin. Therefore, identifying the characteristics of these women may help define optimal therapeutic strategy.

METHODS

This is a retrospective cohort study done in a District General Hospital, UK. GDM was diagnosed by 75 g OGTT test between 24 and 28 weeks of gestation with fasting levels of ≥6.1 mmol/l and/or 2 h postprandial (PP) level of ≥7.8 mmol/l. Logistic regression and receiver operator curves (ROC) were performed to identify the predictors of metformin failure.

RESULTS

Out of 228 women with GDM included, 46/228 (20.2%) and 151/228 (66.2%) received insulin and metformin as first-line medication respectively. Among the metformin-treated, 13 stopped treatment and were excluded from analysis. Of the included 138 metformin-treated women, 77 (55.8%) required supplementary insulin (metformin failure). Metformin failure group had higher maternal age and fasting glucose level at OGTT, HbA1c at OGTT and earlier gestational age (GA) at medication initiation. Metformin failure was predicted if fasting OGTT level >4.8 mmol/l (69% sensitivity and 62% specificity). If the fasting levels of IADPSG (International Association of Diabetes and Pregnancy Study Groups) criteria and NICE (National Institute of Health and Care Excellence) were used, the positive predictive value was 78% and 77% respectively.

CONCLUSION

As women with higher fasting glucose levels have higher chance of necessitating insulin in later pregnancies, appropriate addition of insulin at metformin initiation for these women could help better glycaemic control throughout pregnancy.

Foetoplacental epigenetic changes associated with maternal metabolic dysfunction

Metabolic-related diseases are attributed to a sedentary lifestyle and eating habits, and there is now an increased awareness regarding pregnancy as a preponderant window in the programming of adulthood health and disease. The developing foetus is susceptible to the maternal environment; hence, any unfavourable condition will result in foetal physiological adaptations that could have a permanent impact on its health. Some of these alterations are maintained via epigenetic modifications capable of modifying gene expression in metabolism-related genes. Children born to mothers with dyslipidaemia, pregestational or gestational obesity, and gestational diabetes mellitus, have a predisposition to develop metabolic alterations during adulthood. CpG methylation-associated alterations to the expression of several genes in the human placenta play a crucial role in the mother-to-foetus transfer of nutrients and macromolecules. Identification of epigenetic modifications in metabolism-related tissues of offspring from metabolic-altered pregnancies is essential to obtain insights into foetal programming controlling newborn, childhood, and adult metabolism. This review points out the importance of the foetal milieu in the programming and development of human disease and provides evidence of this being the underlying mechanism for the development of adulthood metabolic disorders in maternal dyslipidaemia, pregestational or gestational obesity, and gestational diabetes mellitus.

Metformin Use in PCOS Pregnancies Increases the Risk of Offspring Overweight at 4 Years of Age: Follow-Up of Two RCTs

CONTEXT

Metformin is used in pregnancy in women with gestational diabetes mellitus, polycystic ovary syndrome (PCOS), and obesity. Metformin passes the placenta.

OBJECTIVE

To explore the effects of metformin use in PCOS pregnancies on offspring growth to 4 years of age.

DESIGN

Follow-up study of two randomized, double-blind, placebo-controlled trials.

SETTING

Secondary care centers. Eleven public hospitals in Norway.

PARTICIPANTS

One hundred eighty-two children of mothers with PCOS who participated in two randomized controlled trials.

INTERVENTION

Metformin 1700 or 2000 mg/d or placebo from first trimester to delivery in the original studies. No intervention in the current study.

MAIN OUTCOME MEASURES

Height, weight, body mass index (BMI), and overweight/obesity at 4 years of age and head circumference at 1 year of age, converted to z scores.

RESULTS

The difference in height z score means between the groups at 4 years of age was nonsignificant (0.07 [95% confidence interval (CI): -0.22 to 0.36]; P = 0.651). At 4 years of age, the metformin group had higher weight z score than the placebo group [difference in means: 0.38 (0.07 to 0.69); P = 0.017] and higher BMI z score [difference in means: 0.45 (0.11 to 0.78); P = 0.010]. There were more overweight/obese children in the metformin group [26 (32%)] than in the placebo group [14 (18%)] at 4 years of age [odds ratio: 2.17 (1.04 to 4.61); P = 0.038]. The difference in mean head circumference z score at 1 year of age was 0.27 (-0.04 to 0.58; P = 0.093).

CONCLUSION

Metformin-exposed children had higher BMI and increased prevalence of overweight/obesity at 4 years of age.

Outcomes for Women with Gestational Diabetes Treated with Metformin: A Retrospective, Case-Control Study

Metformin is increasingly being used a therapeutic option for the management of gestational diabetes mellitus (GDM). The aim of this study was to compare the maternal characteristics and perinatal outcomes of women with GDM treated with metformin (with or without supplemental insulin) with those receiving other management approaches. A retrospective, case-control study was carried out and 83 women taking metformin were matched 1:1 with women receiving insulin or diet and lifestyle modification alone. Women managed with diet and lifestyle modification had a significantly lower fasting plasma glucose (p < 0.001) and HbA1c (p < 0.01) at diagnosis of GDM. Furthermore, women managed with metformin had a higher early pregnancy body mass index (BMI) compared to those receiving insulin or diet and lifestyle modification (p < 0.001). There was no difference in mode of delivery, birth weight or incidence of large- or small-for-gestational-age neonates between groups. Women receiving glucose lowering therapies had a higher rate of neonatal hypoglycaemia (p < 0.05). The incidence of other adverse perinatal outcomes was similar between groups. Despite their greater BMI, women with metformin-treated GDM did not have an increased risk of adverse perinatal outcomes. Metformin is a useful alternative to insulin in the management of GDM.

The identification and treatment of women with hyperglycaemia in pregnancy: an analysis of individual participant data, systematic reviews, meta-analyses and an economic evaluation

BACKGROUND

Gestational diabetes mellitus (GDM) is associated with a higher risk of important adverse outcomes. Practice varies and the best strategy for identifying and treating GDM is unclear.

AIM

To estimate the clinical effectiveness and cost-effectiveness of strategies for identifying and treating women with GDM.

METHODS

We analysed individual participant data (IPD) from birth cohorts and conducted systematic reviews to estimate the association of maternal glucose levels with adverse perinatal outcomes; GDM prevalence; maternal characteristics/risk factors for GDM; and the effectiveness and costs of treatments. The cost-effectiveness of various strategies was estimated using a decision tree model, along with a value of information analysis to assess where future research might be worthwhile. Detailed systematic searches of MEDLINE^® and MEDLINE In-Process & Other Non-Indexed Citations^®, EMBASE, Cumulative Index to Nursing and Allied Health Literature Plus, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, Health Technology Assessment database, NHS Economic Evaluation Database, Maternity and Infant Care database and the Cochrane Methodology Register were undertaken from inception up to October 2014.

RESULTS

We identified 58 studies examining maternal glucose levels and outcome associations. Analyses using IPD alone and the systematic review demonstrated continuous linear associations of fasting and post-load glucose levels with adverse perinatal outcomes, with no clear threshold below which there is no increased risk. Using IPD, we estimated glucose thresholds to identify infants at high risk of being born large for gestational age or with high adiposity; for South Asian (SA) women these thresholds were fasting and post-load glucose levels of 5.2 mmol/l and 7.2 mmol/l, respectively and for white British (WB) women they were 5.4 and 7.5 mmol/l, respectively. Prevalence using IPD and published data varied from 1.2% to 24.2% (depending on criteria and population) and was consistently two to three times higher in SA women than in WB women. Lowering thresholds to identify GDM, particularly in women of SA origin, identifies more women at risk, but increases costs. Maternal characteristics did not accurately identify women with GDM; there was limited evidence that in some populations risk factors may be useful for identifying low-risk women. Dietary modification additional to routine care reduced the risk of most adverse perinatal outcomes. Metformin (Glucophage,^® Teva UK Ltd, Eastbourne, UK) and insulin were more effective than glibenclamide (Aurobindo Pharma - Milpharm Ltd, South Ruislip, Middlesex, UK). For all strategies to identify and treat GDM, the costs exceeded the health benefits. A policy of no screening/testing or treatment offered the maximum expected net monetary benefit (NMB) of £1184 at a cost-effectiveness threshold of £20,000 per quality-adjusted life-year (QALY). The NMB for the three best-performing strategies in each category (screen only, then treat; screen, test, then treat; and test all, then treat) ranged between -£1197 and -£1210. Further research to reduce uncertainty around potential longer-term benefits for the mothers and offspring, find ways of improving the accuracy of identifying women with GDM, and reduce costs of identification and treatment would be worthwhile.

LIMITATIONS

We did not have access to IPD from populations in the UK outside of England. Few observational studies reported longer-term associations, and treatment trials have generally reported only perinatal outcomes.

CONCLUSIONS

Using the national standard cost-effectiveness threshold of £20,000 per QALY it is not cost-effective to routinely identify pregnant women for treatment of hyperglycaemia. Further research to provide evidence on longer-term outcomes, and more cost-effective ways to detect and treat GDM, would be valuable.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013004608.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Risk of pre-eclampsia in women taking metformin: a systematic review and meta-analysis

AIMS

To perform meta-analyses of studies evaluating the risk of pre-eclampsia in high-risk insulin-resistant women taking metformin prior to, or during pregnancy.

METHODS

A search was conducted of the Medline, EMBASE, Web of Science and Scopus databases. Both randomized controlled trials and prospective observational cohort studies of metformin treatment vs. placebo/control or insulin either prior to or during pregnancy were selected. The main outcome measure was the incidence of pre-eclampsia in each treatment group.

RESULTS

Overall, in five randomized controlled trials comparing metformin treatment (n = 611) with placebo/control (n = 609), no difference in the risk of pre-eclampsia was found [combined/pooled risk ratio (RR), 0.86 (95% CI 0.33-2.26); P = 0.76; I²  = 66%]. Meta-analysis of four cohort studies again showed no significant effect [RR, 1.21 (95% CI 0.56-2.61); P = 0.62; I²  = 30%]. A meta-analysis of eight randomized controlled trials comparing metformin (n = 838) with insulin (n = 836), however, showed a reduced risk of pre-eclampsia with metformin [RR, 0.68 (95% CI 0.48-0.95); P = 0.02; I²  = 0%]. No heterogeneity was present in the metformin vs. insulin analysis of randomized controlled trials, whereas high levels of heterogeneity were present in studies comparing metformin with placebo/control. Pre-eclampsia was a secondary outcome in most of the studies. The mean weight gain from time of enrolment to delivery was lower in the metformin group (P = 0.05, metformin vs. placebo; P = 0.004, metformin vs. insulin).

CONCLUSIONS

In studies randomizing pregnant women to glucose-lowering therapy, metformin was associated with lower gestational weight gain and a lower risk of pre-eclampsia compared with insulin.

Insulin for the treatment of women with gestational diabetes

BACKGROUND

Gestational diabetes mellitus (GDM) is associated with short- and long-term complications for the mother and her infant. Women who are unable to maintain their blood glucose concentration within pre-specified treatment targets with diet and lifestyle interventions will require anti-diabetic pharmacological therapies. This review explores the safety and effectiveness of insulin compared with oral anti-diabetic pharmacological therapies, non-pharmacological interventions and insulin regimens.

OBJECTIVES

To evaluate the effects of insulin in treating women with gestational diabetes.

SEARCH METHODS

We searched Pregnancy and Childbirth's Trials Register (1 May 2017), ClinicalTrials.gov, WHO International Clinical Trials Registry Platform (ICTRP) (1 May 2017) and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials (including those published in abstract form) comparing:a) insulin with an oral anti-diabetic pharmacological therapy;b) with a non-pharmacological intervention;c) different insulin analogues;d) different insulin regimens for treating women with diagnosed with GDM.We excluded quasi-randomised and trials including women with pre-existing type 1 or type 2 diabetes. Cross-over trials were not eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study eligibility, risk of bias, and extracted data. Data were checked for accuracy.

MAIN RESULTS

We included 53 relevant studies (103 publications), reporting data for 7381 women. Forty-six of these studies reported data for 6435 infants but our analyses were based on fewer number of studies/participants.Overall, the risk of bias was unclear; 40 of the 53 included trials were not blinded. Overall, the quality of the evidence ranged from moderate to very low quality. The primary reasons for downgrading evidence were imprecision, risk of bias and inconsistency. We report the results for our maternal and infant GRADE outcomes for the main comparison. Insulin versus oral anti-diabetic pharmacological therapyFor the mother, insulin was associated with an increased risk for hypertensive disorders of pregnancy (not defined) compared to oral anti-diabetic pharmacological therapy (risk ratio (RR) 1.89, 95% confidence interval (CI) 1.14 to 3.12; four studies, 1214 women; moderate-quality evidence). There was no clear evidence of a difference between those who had been treated with insulin and those who had been treated with an oral anti-diabetic pharmacological therapy for the risk of pre-eclampsia (RR 1.14, 95% CI 0.86 to 1.52; 10 studies, 2060 women; moderate-quality evidence); the risk of birth by caesarean section (RR 1.03, 95% CI 0.93 to 1.14; 17 studies, 1988 women; moderate-quality evidence); or the risk of developing type 2 diabetes (metformin only) (RR 1.39, 95% CI 0.80 to 2.44; two studies, 754 women; moderate-quality evidence). The risk of undergoing induction of labour for those treated with insulin compared with oral anti-diabetic pharmacological therapy may possibly be increased, although the evidence was not clear (average RR 1.30, 95% CI 0.96 to 1.75; three studies, 348 women; I² = 32%; moderate-quality of evidence). There was no clear evidence of difference in postnatal weight retention between women treated with insulin and those treated with oral anti-diabetic pharmacological therapy (metformin) at six to eight weeks postpartum (MD -1.60 kg, 95% CI -6.34 to 3.14; one study, 167 women; low-quality evidence) or one year postpartum (MD -3.70, 95% CI -8.50 to 1.10; one study, 176 women; low-quality evidence). The outcomes of perineal trauma/tearing or postnatal depression were not reported in the included studies.For the infant, there was no evidence of a clear difference between those whose mothers had been treated with insulin and those treated with oral anti-diabetic pharmacological therapies for the risk of being born large-for-gestational age (average RR 1.01, 95% CI 0.76 to 1.35; 13 studies, 2352 infants; moderate-quality evidence); the risk of perinatal (fetal and neonatal death) mortality (RR 0.85; 95% CI 0.29 to 2.49; 10 studies, 1463 infants; low-quality evidence);, for the risk of death or serious morbidity composite (RR 1.03, 95% CI 0.84 to 1.26; two studies, 760 infants; moderate-quality evidence); the risk of neonatal hypoglycaemia (average RR 1.14, 95% CI 0.85 to 1.52; 24 studies, 3892 infants; low-quality evidence); neonatal adiposity at birth (% fat mass) (mean difference (MD) 1.6%, 95% CI -3.77 to 0.57; one study, 82 infants; moderate-quality evidence); neonatal adiposity at birth (skinfold sum/mm) (MD 0.8 mm, 95% CI -2.33 to 0.73; random-effects; one study, 82 infants; very low-quality evidence); or childhood adiposity (total percentage fat mass) (MD 0.5%; 95% CI -0.49 to 1.49; one study, 318 children; low-quality evidence). Low-quality evidence also found no clear differences between groups for rates of neurosensory disabilities in later childhood: hearing impairment (RR 0.31, 95% CI 0.01 to 7.49; one study, 93 children), visual impairment (RR 0.31, 95% CI 0.03 to 2.90; one study, 93 children), or any mild developmental delay (RR 1.07, 95% CI 0.33 to 3.44; one study, 93 children). Later infant mortality, and childhood diabetes were not reported as outcomes in the included studies.We also looked at comparisons for regular human insulin versus other insulin analogues, insulin versus diet/standard care, insulin versus exercise and comparisons of insulin regimens, however there was insufficient evidence to determine any differences for many of the key health outcomes. Please refer to the main results for more information about these comparisons.

AUTHORS' CONCLUSIONS

The main comparison in this review is insulin versus oral anti-diabetic pharmacological therapies. Insulin and oral anti-diabetic pharmacological therapies have similar effects on key health outcomes. The quality of the evidence ranged from very low to moderate, with downgrading decisions due to imprecision, risk of bias and inconsistency.For the other comparisons of this review (insulin compared with non-pharmacological interventions, different insulin analogies or different insulin regimens), there is insufficient volume of high-quality evidence to determine differences for key health outcomes.Long-term maternal and neonatal outcomes were poorly reported for all comparisons.The evidence suggests that there are minimal harms associated with the effects of treatment with either insulin or oral anti-diabetic pharmacological therapies. The choice to use one or the other may be down to physician or maternal preference, availability or severity of GDM. Further research is needed to explore optimal insulin regimens. Further research could aim to report data for standardised GDM outcomes.

Glibenclamide and metfoRmin versus stAndard care in gEstational diabeteS (GRACES): a feasibility open label randomised trial

BACKGROUND

Metformin is widely used to treat gestational diabetes (GDM), but many women remain hyperglycaemic and require additional therapy. We aimed to determine recruitment rate and participant throughput in a randomised trial of glibenclamide compared with standard therapy insulin (added to maximum tolerated metformin) for treatment of GDM.

METHODS

We conducted an open label feasibility study in 5 UK antenatal clinics among pregnant women 16 to 36 weeks' gestation with metformin-treated GDM. Women failing to achieve adequate glycaemic control on metformin monotherapy were randomised to additional glibenclamide or insulin. The primary outcome was recruitment rate. We explored feasibility with uptake, retention, adherence, safety, glycaemic control, participant satisfaction and clinical outcomes.

RESULTS

Records of 197 women were screened and 23 women randomised to metformin and glibenclamide (n = 13) or metformin and insulin (n = 10). Mean (SD) recruitment rate was 0.39 (0.62) women/centre/month. 9/13 (69.2%, 95%CI 38.6-90.9%) women adhered to glibenclamide and all provided outcome data (100% retention). There were no episodes of severe hypoglycaemia, but metformin and insulin gave superior glycaemic control to metformin and glibenclamide, with fewer blood glucose readings <3.5 mmol/l (median [IQR] difference/woman/week of treatment 0.58 [0.03-1.87]).

CONCLUSIONS

A large randomised controlled trial comparing glibenclamide or insulin in combination with metformin for women with GDM would be feasible but is unlikely to be worthwhile, given the poorer glycaemic control with glibenclamide and metformin in this pilot study. The combination of metformin and glibenclamide should be reserved for women with GDM with true needle phobia or inability to use insulin therapy.

TRIAL REGISTRATION

www.clinicaltrials.gov registration number:NCT02080377 February 11th 2014.

Comparative efficacy and safety of oral antidiabetic drugs and insulin in treating gestational diabetes mellitus: An updated PRISMA-compliant network meta-analysis

BACKGROUND

The safety and efficacy of different drugs in treatment of gestational diabetes mellitus (GDM) patients who could not maintain normal glucose level only through diet and exercise remains to be debated. We performed this network meta-analysis (NAM) to compare and rank different antidiabetic drugs in glucose level control and pregnancy outcomes in GDM patients.

METHODS

We searched PubMed, Cochrane Library, Web of Science, and Embase up to December 31, 2016. Randomized controlled trials (RCTs) related to different drugs in the treatment of GDM patients were enrolled. We extracted the relevant information and assessed the risk of bias with the Cochrane risk of bias tool. We did pair-wise meta-analyses using the fixed-effects model or random-effects model and then adopted random-effects NAM combining both direct and indirect evidence within a Bayesian framework, to calculate the odds ratio (OR) or standardized mean difference (SMD) and to draw a surface under the cumulative ranking curve of the neonatal and maternal outcomes of different treatments in GDM patients.

RESULTS

Thirty-two randomized controlled trials (RCTs) were included in this NAM, including 6 kinds of treatments (metformin, metformin plus insulin, insulin, glyburide, acarbose, and placebo). The results of the NAM showed that regarding the incidence of macrosomia and LGA, metformin had lower incidence than glyburide (OR, 0.5411 and 0.4177). In terms of the incidence of admission to the NICU, insulin had higher incidence compared with glyburide (OR, 1.844). As for the incidence of neonatal hypoglycemia, metformin had lower incidence than insulin and glyburide (OR, 0.6331 and 0.3898), and insulin was lower than glyburide (OR, 0.6236). For mean birth weight, metformin plus insulin was lower than insulin (SMD, -0.5806), glyburide (SMD, -0.7388), and placebo (SMD, -0.6649). Besides, metformin was observed to have lower birth weight than glyburide (SMD, 0.2591). As for weight gain, metformin and metformin plus insulin were lower than insulin (SMD, -0.9166, -1.53). Ranking results showed that glyburide might be the optimum treatment regarding average glucose control, and metformin is the fastest in glucose control for GDM patients; glyburide have the highest incidence of macrosomia, preeclampsia, hyperbilirubinemia, neonatal hypoglycemia, shortest gestational age at delivery, and lowest mean birth weight; metformin (plus insulin when required) have the lowest incidence of macrosomia, PIH, LGA, RDS, low gestational age at delivery, and low birth weight. Besides, insulin had the highest incidence of NICU admission, acarbose had the lowest risk of neonatal hypoglycemia.

CONCLUSION

Our study concluded that metformin is fastest in glucose control, with a more favorable pregnancy outcomes-would be a better option, but its rate of glucose control is the lowest.However, glyburide is the optimumtreatment regarding the rate of glucose control, but withmore adverse outcomes. This NAMbased on 32 RCTs will strongly help to guide further development of management for GDM patients, clinicians should carefully balance the risk-benefit profile of different treatments according to various situations.

Metformin, the aspirin of the 21st century: its role in gestational diabetes mellitus, prevention of preeclampsia and cancer, and the promotion of longevity

Metformin is everywhere. Originally introduced in clinical practice as an antidiabetic agent, its role as a therapeutic agent is expanding to include treatment of prediabetes mellitus, gestational diabetes mellitus, and polycystic ovarian disease; more recently, experimental studies and observations in randomized clinical trials suggest that metformin could have a place in the treatment or prevention of preeclampsia. This article provides a brief overview of the history of metformin in the treatment of diabetes mellitus and reviews the results of metaanalyses of metformin in gestational diabetes mellitus as well as the treatment of obese, non-diabetic, pregnant women to prevent macrosomia. We highlight the results of a randomized clinical trial in which metformin administration in early pregnancy did not reduce the frequency of large-for-gestational-age infants (the primary endpoint) but did decrease the frequency of preeclampsia (a secondary endpoint). The mechanisms by which metformin may prevent preeclampsia include a reduction in the production of antiangiogenic factors (soluble vascular endothelial growth factor receptor-1 and soluble endoglin) and the improvement of endothelial dysfunction, probably through an effect on the mitochondria. Another potential mechanism whereby metformin may play a role in the prevention of preeclampsia is its ability to modify cellular homeostasis and energy disposition, mediated by rapamycin, a mechanistic target. Metformin has a molecular weight of 129 Daltons and therefore readily crosses the placenta. There is considerable evidence to suggest that this agent is safe during pregnancy. New literature on the role of metformin as a chemotherapeutic adjuvant in the prevention of cancer and in prolonging life and protecting against aging is reviewed briefly. Herein, we discuss the mechanisms of action and potential benefits of metformin.

Comparison of glyburide and insulin in the management of gestational diabetes: A meta-analysis

Objective

The aim of this meta-analysis was to determine the efficacy and safety of glyburide as a treatment for gestational diabetes mellitus (GDM) compared to insulin.

Methods

A meta-analysis was conducted to compare the management of gestational diabetes with glyburide and insulin. Studies fulfilling all of the following inclusion criteria were included in this meta-analysis: subjects were women with gestational diabetes requiring drug treatment; the comparison treatment included glyburide vs insulin; one or more outcomes (maternal or neonatal) should be provided in the individual study; the study design should be a randomized control trial. Exclusion criteria: non-RCT studies; non-human data. PubMed, Embase and CENTRAL databases were searched from inception until 10 October 2016.

Results

Ten randomized control trials involving 1194 participants met the inclusion criteria and were included. 13 primary outcomes (6 maternal, 7 neonatal) and 26 secondary outcomes (9 maternal, 17 neonatal) were detected and analyzed in this study. Glyburide significantly increased the risk of any neonatal hypoglycemia [risk ratio (RR), 1.89; 95% confidence interval (95%CI), 1.26 to 2.82; p = 0.002]. Sensitivity analysis confirmed robustness of this result [RR, 2.29; 95%CI, 1.49 to 3.54; p = 0.0002]. No differences were observed between the two groups with respect to birth weights [mean difference (MD), 79; 95%CI, -64 to 221.99; p = 0.28] and the risk of macrosomia [RR, 1.69; 95%CI, 0.57 to 5.08; p = 0.35].

Conclusion

For women with gestational diabetes, no differences in maternal short term outcomes were observed in those treated with glyburide or insulin. However, the incidence of neonatal hypoglycemia was higher in the glyburide group compared to the insulin group.

Treatments for gestational diabetes: a systematic review and meta-analysis

OBJECTIVE

To investigate the effectiveness of different treatments for gestational diabetes mellitus (GDM).

DESIGN

Systematic review, meta-analysis and network meta-analysis.

METHODS

Data sources were searched up to July 2016 and included MEDLINE and Embase. Randomised trials comparing treatments for GDM (packages of care (dietary and lifestyle interventions with pharmacological treatments as required), insulin, metformin, glibenclamide (glyburide)) were selected by two authors and double checked for accuracy. Outcomes included large for gestational age, shoulder dystocia, neonatal hypoglycaemia, caesarean section and pre-eclampsia. We pooled data using random-effects meta-analyses and used Bayesian network meta-analysis to compare pharmacological treatments (ie, including treatments not directly compared within a trial).

RESULTS

Forty-two trials were included, the reporting of which was generally poor with unclear or high risk of bias. Packages of care varied in their composition and reduced the risk of most adverse perinatal outcomes compared with routine care (eg, large for gestational age: relative risk0.58 (95% CI 0.49 to 0.68; I2=0%; trials 8; participants 3462). Network meta-analyses suggest that metformin had the highest probability of being the most effective treatment in reducing the risk of most outcomes compared with insulin or glibenclamide.

CONCLUSIONS

Evidence shows that packages of care are effective in reducing the risk of most adverse perinatal outcomes. However, trials often include few women, are poorly reported with unclear or high risk of bias and report few outcomes. The contribution of each treatment within the packages of care remains unclear. Large well-designed and well-conducted trials are urgently needed.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42013004608.

Scientific Evidence for Different Options for GDM Screening and Management: Controversies and Review of the Literature

Background. Gestational diabetes (GDM) affects up to 7% of pregnant women and is associated with several maternal and perinatal morbidities. International organizations suggest several different recommendations regarding how to screen and to manage GDM. Objective. We aimed to analyze the most important and employed guidelines about screening and management of GDM and we investigated existing related literature. Results. We found several different criteria for screening for GDM, for monitoring GDM, and for starting pharmacological therapy. When using IADPSG criteria, GDM rate increased, perinatal outcomes improved, and screening became cost-effective. Compared to no treatment, treatment of women meeting criteria for GDM by IADPSG criteria but not by other less strict criteria has limited evidence for an effect on adverse pregnancy outcomes.

[Gestational diabetes mellitus]

Gestational diabetes (GDM) is defined as any degree of glucose intolerance with onset during pregnancy and is associated with increased feto-maternal morbidity as well as long-term complications in mothers and offspring. Women detected to have diabetes early in pregnancy receive the diagnosis of overt, non-gestational, diabetes (glucose: fasting > 126 mg/dl, spontaneous > 200 mg/dl or HbA1c > 6.5 % before 20 weeks of gestation). GDM is diagnosed by an oral glucose tolerance test (OGTT) or fasting glucose concentrations (> 92 mg/dl). Screening for undiagnosed type 2 diabetes at the first prenatal visit (Evidence level B) is recommended in women at increased risk using standard diagnostic criteria (high risk: history of GDM or pre-diabetes (impaired fasting glucose or impaired glucose tolerance); malformation, stillbirth, successive abortions or birth weight > 4,500 g in previous pregnancies; obesity, metabolic syndrome, age > 45 years, vascular disease; clinical symptoms of diabetes (e. g. glucosuria)). Performance of the OGTT (120 min; 75 g glucose) may already be indicated in the first trimester in some women but is mandatory between 24 and 28 gestational weeks in all pregnant women with previous non-pathological glucose metabolism (Evidence level B). Based on the results of the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study GDM is defined, if fasting venous plasma glucose exceeds 92 mg/dl or 1 h 180 mg/dl or 2 h 153 mg/dl after glucose loading (OGTT; international consensus criteria). In case of one pathological value a strict metabolic control is mandatory. This diagnostic approach was recently also recommended by the WHO. All women should receive nutritional counseling and be instructed in blood glucose self-monitoring and to increase physical activity to moderate intensity levels- if not contraindicated. If blood glucose levels cannot be maintained in the normal range (fasting < 95 mg/dl and 1 h after meals < 140 mg/dl) insulin therapy should be initiated as first choice. Maternal and fetal monitoring is required in order to minimize maternal and fetal/neonatal morbidity and perinatal mortality. After delivery all women with GDM have to be reevaluated as to their glucose tolerance by a 75 g OGTT (WHO criteria) 6-12 weeks postpartum and every 2 years in case of normal glucose tolerance (Evidence level B). All women have to be instructed about their (sevenfold increased relative) risk of type 2 diabetes at follow-up and possibilities for diabetes prevention, in particular weight management and maintenance/increase of physical activity. Monitoring of the development of the offspring and recommendation of healthy lifestyle of the children and family is recommended.

Neonatal outcomes according to different therapies for gestational diabetes mellitus

OBJECTIVES

To compare different neonatal outcomes according to the different types of treatments used in the management of gestational diabetes mellitus.

METHODS

This was a retrospective cohort study. The study population comprised pregnant women with gestational diabetes treated at a public maternity hospital from July 2010 to August 2014. The study included women aged at least 18 years, with a singleton pregnancy, who met the criteria for gestational diabetes mellitus. Blood glucose levels, fetal abdominal circumference, body mass index and gestational age were considered for treatment decision-making. The evaluated neonatal outcomes were: type of delivery, prematurity, weight in relation to gestational age, Apgar at 1 and 5min, and need for intensive care unit admission.

RESULTS

The sample consisted of 705 pregnant women. The neonatal outcomes were analyzed based on the treatment received. Women treated with metformin were less likely to have children who were small for gestational age (95% CI: 0.09-0.66) and more likely to have a newborn adequate for gestational age (95% CI: 1.12-3.94). Those women treated with insulin had a lower chance of having a preterm child (95% CI: 0.02-0.78). The combined treatment with insulin and metformin resulted in higher chance for a neonate to be born large for gestational age (95% CI: 1.14-11.15) and lower chance to be born preterm (95% CI: 0.01-0.71). The type of treatment did not affect the mode of delivery, Apgar score, and intensive care unit admission.

CONCLUSIONS

The pediatrician in the delivery room can expect different outcomes for diabetic mothers based on the treatment received.

Short- and long-term outcomes of metformin compared with insulin alone in pregnancy: a systematic review and meta-analysis

AIM

To assess the short- and long-term maternal and fetal impact of metformin in pregnancy compared with insulin.

METHODS

We performed a comprehensive literature search of MEDLINE, EMBASE, BIOSIS, Cochrane Database of Systematic Reviews and ClinicalTrials.gov. Eligible studies were randomized control trials (RCTs) or follow-up of an RCT that: (1) compared metformin with insulin in pregnancy in women with gestational diabetes mellitus or Type 2 diabetes; and (2) reported maternal or fetal outcomes of interest. Two reviewers extracted the data, evaluated study quality and calculated pooled estimates.

RESULTS

Sixteen studies (n = 2165 in quantitative analysis) were included. Metformin lowered the risk of neonatal hypoglycaemia [risk ratio (RR) = 0.63; 95% confidence interval (95% CI), 0.45 to 0.87], large for gestational age babies (RR = 0.80; 95% CI, 0.64 to 0.99), pregnancy-induced hypertension (RR = 0.56; 95% CI, 0.37 to 0.85) and total maternal pregnancy weight gain [mean difference (MD) -2.07; 95% CI -2.88 to -1.27]. Metformin did not increase preterm delivery (RR = 1.18; 95% CI 0.67 to 2.07), small for gestational age babies (RR = 1.20; 95% CI, 0.67 to 2.14), perinatal mortality (RR = 0.82; 95% CI, 0.17 to 3.92) or Caesarean section (RR = 0.97; 95% CI, 0.80 to 1.19). Long-term outcome information is limited.

CONCLUSIONS

Our review found that metformin had no short-term adverse effects on pregnancy, potential benefits in the neonatal period, but limited long-term follow-up information. Prior to routine use, we recommend further follow-up studies of offspring exposed to metformin in utero.

Clinical management of pregnancy in the obese mother: before conception, during pregnancy, and post partum

The global epidemic of obesity has led to an increasing number of obese women of reproductive age. Obesity is associated with reduced fertility, and pregnancies complicated by maternal obesity are associated with adverse outcomes, including increased risk of gestational diabetes, pre-eclampsia, preterm birth, instrumental and caesarean births, infections, and post-partum haemorrhage. The medical and obstetric management of obese women is focused on identifying, addressing, and preventing some of these associated complications, and is a daunting challenge given the high percentage of patients with obesity and few therapeutic options proven to improve outcomes in this population. The UK's National Institute for Health and Care Excellence guidelines and the American College of Obstetricians and Gynecologists recommend that all pregnant women follow a healthy diet, and consider at least half an hour of moderate physical activity per day during pregnancy. However, although obese women are often directed to seek the advice of a nutritionist and to limit gestational weight gain, guidelines for the management of pregnancy and delivery in this high-risk group are lacking. The post-partum period represents an important opportunity to optimise maternal health before the next pregnancy. As many of the physiological changes of pregnancy associated with maternal obesity are present from early pregnancy onward, reducing maternal obesity before conception is probably the best strategy to decrease the health burden associated with maternal obesity.

Gestational Diabetes Mellitus:current knowledge and unmet needs

Gestational diabetes mellitus (GDM) is a global health concern, not only because its prevalence is high and on the increase, but also because of the potential implications for the health of mothers and their offspring. Unfortunately, there is considerable controversy in the literature surrounding the diagnosis and treatment of GDM, as well as the possible long-term consequences for the offspring. As a result, worldwide there is a lack of uniformly accepted diagnostic criteria and the advice regarding the treatment of GDM, including diet, insulin therapy, and the use of oral blood glucose-lowering agents, is highly variable. In this review we provide an overview of the important issues in the field of GDM, including diagnostic criteria, different treatment regimens available, and the long-term consequences of GDM in the offspring.

Neuropeptide Y Overexpressing Female and Male Mice Show Divergent Metabolic but Not Gut Microbial Responses to Prenatal Metformin Exposure

Background

Prenatal metformin exposure has been shown to improve the metabolic outcome in the offspring of high fat diet fed dams. However, if this is evident also in a genetic model of obesity and whether gut microbiota has a role, is not known.

Methods

The metabolic effects of prenatal metformin exposure were investigated in a genetic model of obesity, mice overexpressing neuropeptide Y in the sympathetic nervous system and in brain noradrenergic neurons (OE-NPY^DβH). Metformin was given for 18 days to the mated female mice. Body weight, body composition, glucose tolerance and serum parameters of the offspring were investigated on regular diet from weaning and sequentially on western diet (at the age of 5–7 months). Gut microbiota composition was analysed by 16S rRNA sequencing at 10–11 weeks.

Results

In the male offspring, metformin exposure inhibited weight gain. Moreover, weight of white fat depots and serum insulin and lipids tended to be lower at 7 months. In contrast, in the female offspring, metformin exposure impaired glucose tolerance at 3 months, and subsequently increased body weight gain, fat mass and serum cholesterol. In the gut microbiota, a decline in Erysipelotrichaceae and Odoribacter was detected in the metformin exposed offspring. Furthermore, the abundance of Sutterella tended to be decreased and Parabacteroides increased. Gut microbiota composition of the metformin exposed male offspring correlated to their metabolic phenotype.

Conclusion

Prenatal metformin exposure caused divergent metabolic phenotypes in the female and male offspring. Nevertheless, gut microbiota of metformin exposed offspring was similarly modified in both genders.

Hyperglycemia in pregnancy: prevalence, impact, and management challenges

Gestational diabetes mellitus (GDM) is one of the most common medical conditions in pregnancy, and the prevalence is growing with increasing rates of women of advanced age becoming pregnant and the increasing prevalence of maternal obesity and inactivity. GDM is associated with an increased risk of maternal and infant short- and long-term ill-health. There is a positive linear association between increasing maternal glucose at oral glucose tolerance testing and risk of important perinatal outcomes, including cesarean section, large for gestational age, and infant adiposity. A “step-up” approach, where diet and lifestyle information is provided followed by pharmacological interventions as required to control and reduce hyperglycemia, is effective at reducing the risk of macrosomia, but treatment of GDM will increase demand on health services. There is limited evidence to suggest which identification strategy is best or what thresholds should be used to diagnose GDM or what the effects of different diagnostic strategies have on short- or long-term maternal and offspring outcomes. Trials of interventions in pregnancy aimed at preventing GDM have not demonstrated a benefit; therefore, trials are needed to evaluate interventions aimed at optimizing the health of all women of childbearing age, outside of pregnancy. A consistent, evidence-based, sustained approach to supporting women to live healthily, including the achievement of a normal body mass index before and after pregnancy, is urgently needed.

Metformin - a potentially effective drug for gestational diabetes mellitus: a systematic review and meta-analysis

Metformin has been gradually used in the management of gestational diabetes mellitus (GDM). In order to prove the safety and efficacy of metformin used in pregnancy, we searched several databases for the reports of randomized trials comparing insulin and metformin used in GDM and conducted a meta-analysis. Data showed the rates of neonatal large for gestational age, cesarean section, neonatal respiratory distress and preterm birth were similar in both groups. Maternal glycated hemoglobin-% at gestational week 36-37 was significantly lower in metformin group, indicating good glycemic control of metformin. Maternal weight gain since enrollment to gestational week 36-37 was also lower in metformin group, making metformin worth using even when metformin is insufficient and supplementary insulin is needed. Data also showed that metformin significantly reduced the gestational hypertension complications in GDM patients, probably by reducing the endothelial activation and maternal inflammatory response of insulin resistance. Although metformin can cross the placenta, it is less likely to cause severe neonatal hypoglycemia compared with insulin since it neither stimulates pancreatic insulin release nor increases circulating insulin levels. According to most maternal and neonatal outcomes, metformin is an effective and safe alternative to insulin for GDM patients.

Comparison of glyburide with metformin in treating gestational diabetes mellitus: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Controversy has surrounded the treatment of gestational diabetes mellitus (GDM) for a long time. Although the use of both glyburide and metformin are recommended as an alternate to insulin if dietary therapy fails in GDM patients, it remains unclear whether both drugs are equally safe and efficacious. Therefore, in this review we compared the efficacy and safety of glyburide with metformin in treating GDM.

METHODS

A systematic review and meta-analysis of randomized controlled trials was conducted that compared the efficacy and safety of glyburide with metformin in GDM patients. Electronic databases were used to conduct the literature search for study identification along with a hand search of pertinent journals and conference proceedings. The effect measure used to present the results was risk ratio (RR) with 95% confidence interval (CI). A fixed-effects model was used to pool the data if no significant heterogeneity was reported and a random-effects model was used in the case of significant heterogeneity being reported for an outcome.

RESULTS

Three studies involving 508 patients met the inclusion criteria of this review. A significant increase in the risk of the composite outcome, i.e., macrosomia and large for gestational age (LGA) births (RR 1.94; 95% CI 1.03-3.66, p = 0.04), was observed in the glyburide group, whereas a non-significant increase in the risk of neonatal hypoglycemia (RR 1.92; 95% CI 0.31-12.02) was also noticed. Results remained statistically non-significant for preterm births (RR 0.65; 95% CI 0.24-1.77), neonatal birth weight (mean difference (MD) 120.63 g; 95% CI -62.08 to 303.33), and cesarean section (RR 0.86; 95% CI 0.55-1.34). A significant decrease in fasting glucose levels (MD -2.40 mg/dL; 95% CI -4.60 to -0.21; p = 0.03) was noticed in glyburide group while the difference was non-significant for postprandial glucose levels (MD -0.84 mg/dL; 95% CI -4.03 to 2.35).

CONCLUSION

Metformin seems to be a superior choice to glyburide if oral antidiabetic drug therapy is to be initiated in GDM patients.

Is it worth treating gestational diabetes: if so, when and how?

The primary aims of the treatment of gestational diabetes (GDM) are to prevent macrosomia and pregnancy complications. Many large studies and meta-analyses have demonstrated that, compared with usual care, the specific treatment of women with GDM seems to achieve these aims, including lower birthweight and lower rates of shoulder dystocia. Nutritional therapy is a cornerstone of GDM care and is generally recommended as a primary treatment. Medical treatment should be started after 1-2 weeks if normoglycaemia is not achieved with lifestyle changes. This review provides an overview of the current data on and practices for the treatment of GDM and summarises a presentation given at the 'Gestational diabetes: what's up?' symposium at the 2015 annual meeting of the EASD. It is accompanied by two other reviews on topics from this symposium (by Peter Damm and Colleagues, DOI: 10.1007/s00125-016-3985-5 , and by Cuilin Zhang and colleagues, DOI: 10.1007/s00125-016-3979-3 ) and an overview by the Session Chair, Kerstin Berntorp (DOI: 10.1007/s00125-016-3975-7 ).

Identification of metformin poor responders, requiring supplemental insulin, during randomization of metformin versus insulin for the control of gestational diabetes mellitus

AIM

To evaluate glycemic control among women with gestational diabetes mellitus (GDM) under insulin versus metformin (with or without insulin supplementation), and to identify metformin poor responders requiring supplemental insulin.

METHODS

In Ain Shams University Hospital, mothers with 26-32-week GDM pregnancies, failing diet control, were randomized to receive metformin (n = 47) or insulin (n = 48). The primary outcome was glycemic control. Secondary outcomes included maternal weight, parameters predicting successful metformin monotherapy, neonatal hypoglycemia, and birthweight.

RESULTS

Women using metformin (23.4% needing supplemental insulin) gained less weight (P < 0.001), and had lower fasting glucose during the first and last 2 weeks of treatment (P = 0.014 and 0.008, respectively) when compared with insulin monotherapy. Insulin supplementation in the metformin group was related to initial body mass index, HbA1c, oral glucose tolerance test (GTT), and first week mean glucose level. The 1-h glucose level during initial GTT (Hr1-GTT) and the mean fasting glucose level during the first week of therapy (Wk1-mFG) were the two independent parameters associated with requiring supplemental insulin. Women with Hr1-GTT >212 mg/dL and Wk1-mFG >95 mg/dL had a risk ratio of 58.6 (95%CI: 3.68-933.35, P = 0.004) and 11.5 (95%CI: 2.77-47.34,= 0.0008), respectively for needing supplemental insulin during the course of the study compared with women without.

CONCLUSION

Metformin is an effective and safe alternative to insulin in GDM. Women using metformin (± supplemental insulin) had similar glycemic control, less weight gain, and similar rates of side-effects as those on insulin monotherapy. Insulin supplementation to metformin therapy was more likely with elevated Hr1-GTT and Wk1-mFG.

Metformin versus insulin in gestational diabetes mellitus: a meta-analysis of randomized clinical trials

BACKGROUND

Metformin is widely used in treatment of type 2 diabetes. However, whether it is safe for use in pregnancy is controversial.

METHODS

A search for relevant studies were performed using PubMed (1948-2014), Embase (1974-2014), the Web of knowledge (1950-2014), and the Cochrane database, included all randomized control trials published in English.

RESULTS

Eight RCTs (1712 patients with gestational diabetes mellitus) were retrieved; of those 853 patients were given metformin, and 859 patients were given insulin. Our results showed that metformin does not increase risk of prematurity (RR = 1.26; 95 % CI [0.89, 1.79], P = 0.19). In addition, metformin can either decrease the total weight gain [MD = -1.49, 95 % CI (-2.66, -0.31), P = 0.01] or weight gain after randomization [MD = -1.23, 95 % CI (-1.75, -0.71), P < 0.00001]. No significant differences were observed in patients with pre-eclampsia [RR = 0.82, 95 % CI (0.56, 1.2), P = 0.32] or caesarean section [RR = 0.93, 95 % CI (0.75, 1.16), P = 0.53]. Use of metformin also significantly decreased the risk of neonatal hypoglycemia [RR = 0.58, 95 % CI (0.43, 0.78), P = 0.0003] and admission rates to neonatal intensive care units [RR = 0.74, 95 % CI (0.61, 0.89), P = 0.002]. No other adverse effects were observed, such as hyperbilirubinaemia [RR = 0.83, 95 % CI (0.64, 1.08), P = 0.16], large for gestational age [RR = 0.85, 95 % CI (0.68, 1.05), P = 0.14], small for gestational age [RR = 0.92, 95 % CI (0.61, 1.39), P = 0.69], macrosomia [RR = 0.75, 95 % CI (0.54, 1.03), P = 0.07] or respiratory distress syndrome [RR = 0.88, 95 % CI (0.55, 1.41), P = 0.6].

CONCLUSIONS

Metformin may be beneficial in treating gestational diabetes. However, even more studies are needed to provide more evidence for the future use of metformin.

Metformin Treatment Does Not Affect Testicular Size in Offspring Born to Mothers with Gestational Diabetes

OBJECTIVES

Studies in rodents suggest that metformin treatment during pregnancy may have harmful effects on testicular development in offspring. Our aim was to determine whether metformin treatment of gestational diabetes mellitus (GDM) affects testicular size in male offspring.

METHODS

We compared the testicular size in prepubertal boys born to mothers who participated in a randomized controlled trial (RCT) comparing metformin with insulin in the treatment of GDM. Twenty-five (42.4% of invited) and 27 (52.9% of invited) boys whose mothers had been treated with metformin or insulin, respectively, participated in the study. Testicular size was measured by a ruler, an orchidometer, and by ultrasonography at the age of 33 to 85 months.

RESULTS

The mean age of the boys was 60 months at the time of examination, and did not differ between the metformin and insulin group (p = 0.88). There was no difference in testicular size between the boys in the two groups (p always ≥ 0.40), and there were no significant differences in height, weight, BMI, BMI z-score, or waist-to-hip ratio (WHR) between the boys in the groups.

CONCLUSIONS

Prepubertal testicular size did not differ between offspring born to metformin-treated mothers and those born to insulin-treated mothers.

Neurodevelopment of Two-Year-Old Children Exposed to Metformin and Insulin in Gestational Diabetes Mellitus

OBJECTIVE

To compare cognitive, language, and motor skills and results of neurological examination in 2-year-old children born to mothers with gestational diabetes mellitus treated with metformin with those treated with insulin.

METHOD

The children of mothers with gestational diabetes mellitus randomized to metformin (n = 75) or insulin (n = 71) treatment during pregnancy were examined by standardized developmental and neurological measures; the Bayley Scales of Infant and Toddler Development (Bayley-III) and the Hammersmith Infant Neurological Examination.

RESULTS

There were no significant differences between the metformin and insulin groups in the Bayley Scales of Infant and Toddler Development (Bayley-III) test of cognitive scale (p = .12), receptive communication (p = .14) or expressive communication (p = .75), fine motor scale (p = .10) or gross motor scale (p = .13), or the global scores of Hammersmith Infant Neurological Examination (p = .14). None of the children had a clinically significant developmental problem. However, compared with age-adjusted norms, a trend for weaker language performance was observed in both study groups.

CONCLUSION

No differences in neurodevelopmental outcome were seen in 2-year-old children born to mothers with gestational diabetes mellitus (GDM) treated with insulin or metformin during pregnancy. The results suggest that children born to mothers with GDM and exposed to metformin in utero do not systematically need extensive formal neurodevelopmental assessment in early childhood.

A toxicology study to evaluate the embryotoxicity of metformin compared with the hypoglycemic drugs, the anticancer drug, the anti-epileptic drug, the antibiotic, and the cyclo-oxygenase (COX)-2 inhibitor

BACKGROUND

The safe use of medications in pregnant females, their embryos and in offspring is important. The aim of the present study was to evaluate embryotoxicity of metformin (MET) compared with other hypoglycemic drugs (rosiglitazone [RSG] and glimepiride [GLIM]), the anticancer drug 5-fluorouracil (5-FU), the anti-epileptic drug diphenylhydantoin (DPH), the antibiotic penicillin G (PenG), and the cyclo-oxygenase (COX)-2 inhibitor nimesulide (NIM) in an embryonic stem cell test (EST).

METHODS

Differences in the expression of developmental marker genes following treatment with the test compounds during the course of differentiation (from embryonic stem cell D3 (D3 cells) to myocardial cells) were determined using real-time quantitative polymerase chain reaction. In these studies, 5-FU was used as a positive control and PenG was used as a negative control. The cytotoxicity of these drugs against D3 cells and 3T3 fibroblasts was determined by the 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Embryotoxicity was classified according to the prediction model of EST.

RESULTS

At concentrations >800 μg/mL MET had a greater cytotoxic effect on D3 cells than 3T3 fibroblasts. At the highest concentration of MET (5 mg/mL), the cell viability of D3 cells and 3T3 fibroblasts was <10% and >30%, respectively. The size of the embryonic body (EB) differentiation area was almost the same over the concentration range 50-200 μg/mL MET, and there was no significant difference in EB differentiation area until a concentration of 400 μg/mL MET. At a concentration of 800 μg/mL MET, the size of EB outgrowth was significantly reduced. The same assays revealed GLIM, RSG, and NIM to be weakly embryotoxic substances.

CONCLUSIONS

Based on the EST, MET can be classified as a weakly embryotoxic substance, which suggests that it should be prescribed with caution to pregnant women with gestational diabetes.

Metformin for the treatment of gestational diabetes: An updated meta-analysis

OBJECTIVE

To assess the efficacy of metformin and insulin in the treatment of pregnant women with gestational diabetes mellitus (GDM).

METHODS

A meta-analysis was conducted by including randomized controlled trials comparing metformin and insulin in GDM. An electronic search was conducted to identify relevant studies. Data were synthesized by a random effects meta-analysis model. A Bayesian analysis was also performed to account for uncertainties in the treatment efficacy.

RESULTS

Eight clinical trials involving 1712 individuals were included in the final analysis. The pooled estimates of metformin-insulin differences were very small and statistically non-significant in fasting plasma glucose, postprandial plasma glucose and HbA1c, measured at 36-37 weeks of gestation. Notably, 14-46% of those receiving metformin required additional insulin. Compared with the insulin group, metformin treatment was associated with a lower incidence of neonatal hypoglycemia (relative risk, RR 0.74; 95% CI 0.58-0.93; P=0.01) and of neonatal intensive care admission (RR 0.76; 95% CI 0.59-0.97; P=0.03). Bayesian analysis revealed that the efficacy of metformin was consistently higher than insulin with a probability of over 98% on these two neonatal complications. Other outcomes were not significantly different between the two treatment groups.

CONCLUSION

In women with gestational diabetes, metformin use and insulin therapy have comparable glycemic control profile, but metformin use was associated with lower risk of neonatal hypoglycemia.

Oral hypoglycemic agents: do the ends justify the means?

BACKGROUND

Glyburide has replaced insulin as the first line of therapy in the treatment of gestational diabetes in the United States. Glyburide and metformin therapies were reported to be comparable to insulin yet also cost-effective, patient-friendly, and potentially compliance-enhancing. Recently, the efficacy of the use of these oral hypoglycemic drugs has been questioned. In this review, the questionable concerns will be addressed: Which diabetic drug(s) cross the placenta? What is the quality of evidence and the data source validity? Which treatment modalities are most effective in reducing the primary outcome in GDM? Which drug is most effective in improving secondary outcomes?

FINDINGS

This review documents the methodological issues in study design that have impacted the results for the provision of health care interventions in GDM. The review summarizes the contents of the articles qualitatively and assesses the theoretical and empirical evidence. Multiple types of studies exist and every study design serves a specific purpose. Different study designs addressing the same question can yield varying results. The risk of presenting uncertain results without categorically knowing the direction and magnitude of the effect holds true for both randomized and nonrandomized controlled trials. The review further emphasizes the importance of achieving the targeted levels of glycemic control.

CONCLUSION

The implications of this review are critical to addressing the current gaps in the literature on the efficacy of the use of oral hypoglycemic agents in GDM. The emphasis needs to be placed on patient treatment in order to manage hyperglycemia to reduce fetal and maternal morbidity. In this regard, we need to delineate proper outcome criteria that will reflect disease severity and treat using appropriate pharmacological therapy.

A review of current treatment strategies for gestational diabetes mellitus

Approximately 90% of diabetes cases in pregnant women are considered gestational diabetes mellitus (GDM). It is well known that uncontrolled glucose results in poor pregnancy outcomes in both the mother and fetus. Worldwide there are many guidelines with recommendations for appropriate management strategies for GDM once lifestyle modifications have been instituted and failed to achieve control. The efficacy and particularly the safety of other treatment modalities for GDM has been the source of much debate in recent years. Studies that have demonstrated the safety and efficacy of both glyburide and metformin in the management of patients with GDM will be reviewed. There is a lack of evidence with other oral and injectable non-insulin agents to control blood glucose in GDM. The role of insulin will be discussed, with emphasis on insulin analogs. Ideal patient characteristics for each treatment modality will be reviewed. In addition, recommendations for postpartum screening of patients will be described as well as recommendations for use of agents to manage subsequent type 2 diabetes in patients who are breastfeeding.

Metformin versus insulin for gestational diabetes mellitus: a meta-analysis

The aim of the present meta-analysis was to determine the efficacy and safety of metformin for the treatment of women with gestational diabetes mellitus (GDM). We searched databases, including PubMed, Embase and the Cochrane Central Register of Controlled Trials, for randomized controlled trials (RCTs) comparing metformin and insulin treatments in women with GDM. We carried out statistical analyses using RevMan 2011 and used the Grading of Recommendations, Assessment, Development, and Evaluations profiler to rate the quality of evidence of the primary outcomes. We analysed eight studies involving 1592 subjects. Meta-analysis of the RCTs showed that metformin had statistically significant effects on pregnancy-induced hypertension [PIH; risk ratio (RR) 0.54; 95% confidence interval (CI) 0.31, 0.91]. However, its effects on neonatal hypoglycaemia (RR 0.80; 95% CI 0.62, 1.02), rate of large-for-gestational age infants (RR 0.77; 95% CI 0.55, 1.08), respiratory distress syndrome (RR 1.26; 95% CI 0.67, 2.37), phototherapy (RR 0.94; 95% CI 0.67, 1.31) and perinatal death (RR 1.01; 95% CI 0.11, 9.53) were not significant. Our analyses suggest that there is no clinically relevant difference in efficacy or safety between metformin and insulin; however, metformin may be a good choice for GDM because of the lower risk of PIH. The advantages of metformin in terms of glycaemic control, PIH incidence and gestational age at birth are unclear, and should be verified in further trials.

Use of antidiabetic agents in the treatment of gestational diabetes mellitus in Germany, 2008-2012

AIM

Adequate blood glucose control during pregnancy is important because gestational diabetes mellitus (GDM) is known to have adverse effects on the mother and child. Due to an increasing prevalence of GDM in recent years, more information on the use of different antidiabetic agents is required, which was the aim of the present study.

MATERIAL AND METHODS

Data from 32 diabetic practices in Germany were collected from January 2008 to December 2012 and analyzed using the Disease Analyzer Database. All women with International Classification of Diseases diagnosis O24 (that is, GDM) participated, except for patients with known type I or II diabetes mellitus, who were excluded. Analysis focused on the proportion of women requiring drug treatment in general. Thereafter, subanalysis was performed with a focus on the administration of different antidiabetic agents, namely insulin, metformin, and sulfonylurea.

RESULTS

Within the given timeframe, medication-based treatment for GDM significantly rose to reach 30.8% of all women with GDM. Both the administration of insulin and metformin grew considerably within the 5-year period with metformin being increasingly used without supplemental insulin and at lower dosages. Within the insulin treatment arm, insulin analogues became increasingly important. The proportion of sulfonylurea remained stable (0.2%).

CONCLUSIONS

GDM is more often treated with antidiabetic agents and, due to the fact that metformin is more frequently prescribed, it can be assumed that it is increasingly regarded as a safe and effective alternative to insulin.

Metformin treatment in type 2 diabetes in pregnancy: an active controlled, parallel-group, randomized, open label study in patients with type 2 diabetes in pregnancy

AIMS

To assess the effect of metformin and to compare it with insulin treatment in patients with type 2 diabetes in pregnancy in terms of perinatal outcome, maternal complications, additional insulin requirement, and treatment acceptability.

METHODS

In this randomized, open label study, 206 patients with type 2 diabetes in pregnancy who met the eligibility criteria were selected from the antenatal clinics. Insulin was added to metformin treatment when required, to maintain the target glycemic control. The patients were followed up till delivery. Maternal, and perinatal outcomes and pharmacotherapeutic characteristics were recorded on a proforma.

RESULTS

Maternal characteristics were comparable in metformin and insulin treated group. 84.9% patients in metformin group required add-on insulin therapy at mean gestational age of 26.58 ± 3.85 weeks. Less maternal weight gain (P < 0.001) and pregnancy induced hypertension (P = 0.029) were observed in metformin treated group. Small for date babies were more in metformin group (P < 0.01). Neonatal hypoglycemia was significantly less and so was NICU stay of >24 hours in metformin group (P < 0.01). Significant reduction in cost of treatment was found in metformin group.

CONCLUSION

Metformin alone or with add-on insulin is an effective and cheap treatment option for patients with type 2 diabetes in pregnancy. This trial is registered with clinical trial registration number: Clinical trials.gov NCT01855763.

Metformin in gestational diabetes: An emerging contender

Gestational diabetes mellitus (GDM) is defined as any degree of glucose intolerance occurring first time during pregnancy. Its prevalence is simultaneously increasing with the global rise of diabesity. GDM commonly develops, when maternal glucose metabolism is unable to compensate for the progressive development of insulin resistance, arising primarily from the consistently rising diabetogenic placental hormones. It classically develops during the second or third trimester. Theoretically, insulin sensitizers should have been the ideal agent in its treatment, given the insulin resistance, the major culprit in its pathogenesis. Fortunately, majority of women can be treated satisfactorily with lifestyle modification, and approximately 20% requires more intensive treatment. For several decades, insulin has been the most reliable treatment strategy and the gold standard in GDM. Metformin is effective insulin sensitizing agent and an established first line drug in type 2 diabetes currently. As it crosses the placenta, a safety issue remains an obstacle and, therefore, metformin is currently not recommended in the treatment of GDM. Nevertheless, given the emerging clinically equivalent safety and efficacy data of metformin compared to insulin, it appears that it may perhaps open a rather new door in managing GDM. The aim of this review is to critically analyze, the safety and efficacy data of metformin regarding its use in GDM and pregnant mothers with polycystic ovarian disease, which has emerged in past decades.

Oral antidiabetic agents in gestational diabetes: a narrative review of current evidence

Gestational diabetes mellitus (GDM) classically occurs when maternal glucose metabolism is unable to compensate the progressive development of insulin resistance that arises from the continuously rising diabetogenic placental hormones. Although most women can be treated satisfactorily with diet alone, some require more intensive treatment. Insulin has been the most reliable treatment strategy in GDM over several decades. Although a long time has passed since the publication of two randomized controlled trials suggesting comparable efficacy and safety of metformin and glibenclamide, international bodies have not yet approved these oral agents. However, with the consistently emerging efficacy and safety data of these two drugs in the past decade, they may perhaps open a rather new door. The aim of this narrative review is to critically evaluate the existing evidence regarding safety and efficacy of oral drugs in GDM accumulated since the first publication in year 2000, suggesting clinical equivalency of glibenclamide (glyburide).

Glibenclamide, metformin, and insulin for the treatment of gestational diabetes: a systematic review and meta-analysis

OBJECTIVE

To summarize short term outcomes in randomized controlled trials comparing glibenclamide or metformin versus insulin or versus each other in women with gestational diabetes requiring drug treatment.

DESIGN

Systematic review and meta-analysis.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Randomized controlled trials that fulfilled all the following: (1) published as full text; (2) addressed women with gestational diabetes requiring drug treatment; (3) compared glibenclamide v insulin, metformin v insulin, or metformin v glibenclamide; and (4) provided information on maternal or fetal outcomes.

DATA SOURCES

Medline, CENTRAL, and Embase were searched up to 20 May 2014.

OUTCOMES MEASURES

We considered 14 primary outcomes (6 maternal, 8 fetal) and 16 secondary (5 maternal, 11 fetal) outcomes.

RESULTS

We analyzed 15 articles, including 2509 subjects. Significant differences for primary outcomes in glibenclamide v insulin were obtained in birth weight (mean difference 109 g (95% confidence interval 35.9 to 181)), macrosomia (risk ratio 2.62 (1.35 to 5.08)), and neonatal hypoglycaemia (risk ratio 2.04 (1.30 to 3.20)). In metformin v insulin, significance was reached for maternal weight gain (mean difference -1.14 kg (-2.22 to -0.06)), gestational age at delivery (mean difference -0.16 weeks (-0.30 to -0.02)), and preterm birth (risk ratio 1.50 (1.04 to 2.16)), with a trend for neonatal hypoglycaemia (risk ratio 0.78 (0.60 to 1.01)). In metformin v glibenclamide, significance was reached for maternal weight gain (mean difference -2.06 kg (-3.98 to -0.14)), birth weight (mean difference -209 g (-314 to -104)), macrosomia (risk ratio 0.33 (0.13 to 0.81)), and large for gestational age newborn (risk ratio 0.44 (0.21 to 0.92)). Four secondary outcomes were better for metformin in metformin v insulin, and one was worse for metformin in metformin v glibenclamide. Treatment failure was higher with metformin than with glibenclamide.

CONCLUSIONS

At short term, in women with gestational diabetes requiring drug treatment, glibenclamide is clearly inferior to both insulin and metformin, while metformin (plus insulin when required) performs slightly better than insulin. According to these results, glibenclamide should not be used for the treatment of women with gestational diabetes if insulin or metformin is available.Systematic review registration NCT01998113.