Comparison of metformin and insulin in the treatment of gestational diabetes: a retrospective, case-control study

Metformin in gestational diabetes: physiological actions and clinical applications

Metformin is an effective oral hypoglycaemic agent used in the treatment of type 2 diabetes mellitus; however, its use in pregnancy for the treatment of gestational diabetes mellitus (GDM) remains controversial owing to concerns around safety and efficacy. This comprehensive review outlines the physiological metabolic functions of metformin and synthesizes existing literature and key knowledge gaps pertaining to the use of metformin in pregnancy across various end points in women with GDM. On the basis of current evidence, metformin reduces gestational weight gain, neonatal hypoglycaemia and macrosomia and increases insulin sensitivity. However, considerable heterogeneity between existing studies and the grouping of aggregate and often inharmonious data within meta-analyses has led to disparate findings regarding the efficacy of metformin in treating hyperglycaemia in GDM. Innovative analytical approaches with stratification by individual-level characteristics (for example, obesity, ethnicity, GDM severity and so on) and treatment regimens (diagnostic criteria, treatment timing and follow-up duration) are needed to establish efficacy across a range of end points and to identify which, if any, subgroups might benefit from metformin treatment during pregnancy.

Neonatal Outcomes in Patients with Gestational Diabetes Mellitus Treated with Metformin: A Retrospective Study in Saudi Arabia

BACKGROUND

Gestational diabetes mellitus (GDM) is a common endocrine disease that can occur during pregnancy, increasing the risk of fetal morbidity and mortality. Metformin is a commonly used therapeutic approach for managing GDM. However, there is controversy regarding the effects of metformin on fetal outcomes during pregnancy. This study aimed to evaluate the safety of metformin in relation to neonatal complications, compared to treatment with insulin and/or specialized diets.

METHOD

This was a retrospective study that included pregnant women who were diagnosed with GDM and treated with specialized diets, metformin, or insulin. Data were collected from patients' electronic medical records and analyzed to evaluate the risk of neonatal outcomes in the metformin group compared to the others.

RESULTS

The study included 234 women with GDM. There was no difference between the metformin and insulin groups in terms of the rates of neonatal outcomes, while neonatal hypoglycemia, neonatal hyperbilirubinemia, large for gestational age, and respiratory distress were higher in the metformin group when compared to the diet group. Metformin slightly increased the risk of a lower APGAR score compared to diet alone.

CONCLUSIONS

Metformin was found to be a safe therapy for the fetus when used to manage GDM, compared to insulin therapy. More randomized studies are needed to confirm these findings in the Saudi population.

Relationships Between Exposure to Gestational Diabetes Treatment and Neonatal Anthropometry: Evidence from the Born in Bradford (BiB) Cohort

OBJECTIVES

To examine the relationships between gestational diabetes mellitus (GDM) treatment and neonatal anthropometry.

METHODS

Covariate-adjusted multivariable linear regression analyses were used in 9907 offspring of the Born in Bradford cohort. GDM treatment type (lifestyle changes advice only, lifestyle changes and insulin or lifestyle changes and metformin) was the exposure, offspring born to mothers without GDM the control, and birth weight, head, mid-arm and abdominal circumference, and subscapular and triceps skinfold thickness the outcomes.

RESULTS

Lower birth weight in offspring exposed to insulin (- 117.2 g (95% CI - 173.8, - 60.7)) and metformin (- 200.3 g (- 328.5, - 72.1)) compared to offspring not exposed to GDM was partly attributed to lower gestational age at birth and greater proportion of Pakistani mothers in the treatment groups. Higher subscapular skinfolds in offspring exposed to treatment compared to those not exposed to GDM was partly attributed to higher maternal glucose concentrations at diagnosis. In fully adjusted analyses, offspring exposed to GDM treatment had lower weight, smaller abdominal circumference and skinfolds at birth than those not exposed to GDM. Metformin exposure was associated with smaller offspring mid-arm circumference (- 0.3 cm (- 0.6, - 0.07)) than insulin exposure in fully adjusted models with no other differences found.

CONCLUSIONS FOR PRACTICE

Offspring exposed to GDM treatment were lighter and smaller at birth than those not exposed to GDM. Metformin-exposed offspring had largely comparable birth anthropometric characteristics to those exposed to insulin.

Gestational Diabetes Mellitus and Preeclampsia: Correlation and Influencing Factors

Gestational diabetes mellitus (GDM) and preeclampsia (PE) are common pregnancy complications with similar risk factors and pathophysiological changes. Evidence from previous studies suggests that the incidence of PE is significantly increased in women with GDM, but whether GDM is independently related to the occurrence of PE has remained controversial. GDM complicated by PE further increases perinatal adverse events with greater impact on the future maternal and offspring health. Identify factors associated with PE in women with GDM women, specifically those that are controllable, is important for improving pregnancy outcomes. This paper provides the findings of a review on the correlation between GDM and PE, factors associated with PE in women with GDM, possible mechanisms, and predictive markers. Most studies concluded that GDM is independently associated with PE in singleton pregnancy, and optimizing the treatment and management of GDM can reduce the incidence of PE, which is very helpful to improve pregnancy outcomes.

Metformin in pregnancy and risk of adverse long-term outcomes: a register-based cohort study

This study aimed to investigate if maternal pregnancy exposure to metformin is associated with increased risk of long-term and short-term adverse outcomes in the child. RESEARCH DESIGN AND METHODS : This register-based cohort study from Finland included singleton children born 2004-2016 with maternal pregnancy exposure to metformin or insulin (excluding maternal type 1 diabetes): metformin only (n=3967), insulin only (n=5273) and combination treatment (metformin and insulin; n=889). The primary outcomes were long-term offspring obesity, hypoglycemia, hyperglycemia, diabetes, hypertension, polycystic ovary syndrome, and challenges in motor-social development. In a sensitivity analysis, the primary outcomes were investigated only among children with maternal gestational diabetes. Secondary outcomes were adverse outcomes at birth. Analyses were conducted using inverse- probability of treatment weighting (IPTW), with insulin as reference. RESULTS  : Exposure to metformin or combination treatment versus insulin was not associated with increased risk of long-term outcomes in the main or sensitivity analyses. Among the secondary outcomes, increased risk of small for gestational age (SGA) was observed for metformin (IPTW-weighted OR 1.65, 95% CI 1.16 to 2.34); increased risk of large for gestational age, preterm birth and hypoglycemia was observed for combination treatment. No increased risk was observed for neonatal mortality, hyperglycemia, or major congenital anomalies. CONCLUSIONS : This study found no increased long-term risk associated with pregnancy exposure to metformin (alone or in combination with insulin), compared with insulin. The increased risk of SGA associated with metformin versus insulin suggests caution in pregnancies with at-risk fetal undernutrition. The increased risks of adverse outcomes at birth associated with combination treatment may reflect confounding by indication or severity.

Effects of Different Glucose-Lowering Measures on Maternal and Infant Outcomes in Pregnant Women with Gestational Diabetes: A Network Meta-analysis

INTRODUCTION

A network meta-analysis was conducted to compare and rank the effects of different glucose-lowering measures on maternal and infant outcomes in pregnant women with gestational diabetes mellitus (GDM).

METHODS

We searched the PubMed, CNKI, Embase, Cochrane Library, Wanfang, and Weipu databases for relevant studies published between database establishment and June 2021. Study retrieval involved subject-heading and keyword searches. Randomized controlled trials (RCTs) with different glucose-lowering treatments for GDM patients were included. The Cochrane tool was used to assess bias risk. Pairwise and network meta-analyses were used to compare and rank the effects of different hypoglycemic measures on maternal and infant outcomes in pregnant women with GDM.

RESULTS

We included 41 RCTs involving 6245 pregnant women with GDM. Patients treated with insulin had a higher incidence of neonatal intensive care unit (NICU) occupancy (1.3, 95% CI 1.0-1.7) than those treated with metformin. The insulin (1.5, 95% CI 1.1-2.1 and 1.8, 95% CI 1.0-3.3) and glyburide (2.0, 95% CI 1.2-3.2 and 2.5, 95% CI 1.1-8.4) groups exhibited higher incidences of neonatal hypoglycemia and large for gestational age (LGA) newborns than the metformin group. The glyburide group exhibited a lower probability of cesarean section than the metformin (0.76, 95% CI 0.55-1.0) and insulin (0.71, 95% CI 0.52-0.96) groups. Preeclampsia incidence in the diet and exercise groups was significantly lower than in the metformin (0.19, 95% CI 0.043-0.72) and insulin (0.15, 95% CI 0.032-0.52) groups. No intervention significantly reduced the incidences of macrosomia, preterm birth, gestational hypertension, or respiratory distress syndrome (RDS). The ranking results showed that the metformin group had the lowest rates of neonatal hypoglycemia, macrosomia, LGA, and NICU occupancy. The glyburide group had the lowest NICU occupancy and cesarean section rates and the highest neonatal hypoglycemia, LGA, preeclampsia, and gestational hypertension rates. The diet and exercise group had the lowest preterm delivery and preeclampsia rates and the highest NICU occupancy rate.

CONCLUSION

Metformin is a potentially superior choice for GDM treatment because it is associated with minimal incidences of multiple adverse pregnancy outcome indicators and does not lead to high values of certain adverse outcome indices. Other hypoglycemic agent or diet groups exhibit high incidences of certain adverse outcomes. Therefore, when selecting a GDM treatment strategy, the efficacies and risks of different treatment programs should be evaluated according to the scenario in hand.

Gestational Diabetes and Risk Assessment of Adverse Perinatal Outcomes and Newborns Early Motoric Development

Background and Objectives: The aim of this study was to analyze the presence of gestational diabetes mellitus (GDM) on maternal and fetal perinatal parameters, as well to evaluate the influence of GDM on neonatal early motoric development. Materials and Methods: In this prospective study, we evaluated 203 eligible participants that were admitted to obstetrics department for a labor. GDM was assessed by evaluation of maternal parameters, fetal parameters, as well its impact on infants early motoric development (Alberta Infant Motor Scale-AIMS). Results: Presence of GDM was significantly positively associated with: pre-pregnancy weight, obesity degree, weight at delivery, gestational weight gain (GWG), body mass index (BMI) at delivery, GWG and increased pre-pregnancy BMI, glucose levels in mother's venous blood after the delivery, positive family history for cardiovascular disease, pregnancy-related hypertension, congenital thrombophilia, drug use in pregnancy, large for gestational age (LGA), mode of delivery (Cesarean section and instrumental delivery). Likewise, GDM association was detected for tested ultrasound parameters (biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femoral length (FL)), length at birth, birth weight, newborn's head circumference, newborn's chest circumference, AIMS supination and pronation at three months, AIMS supination, pronation, sitting and standing at six months. Only Amniotic Fluid Index and AIMS supination at three months of infant's age remained significantly associated in multivariate regression model. Conclusions: The presence of significant positive association of numerous tested parameters in our study on perinatal outcomes and early motoric development, points to the necessity of establishing appropriate clinical decision-making strategies for all pregnant woman at risk and emphasize the importance of providing adequate glycaemia control options and further regular follow ups during the pregnancy.

Safe threshold of capillary blood glucose for predicting early future neonatal hypoglycaemia in babies born to mothers with gestational diabetes mellitus, an observational, retrospective cohort study

BACKGROUND

There is increasing pressure to get women and babies home rapidly after birth. Babies born to mothers with gestational diabetes mellitus (GDM) currently get 24-h inpatient monitoring. We investigated whether a low-risk group of babies born to mothers with GDM could be defined for shorter inpatient hypoglycaemia monitoring.

METHODS

Observational, retrospective cohort study conducted in a tertiary maternity hospital in 2018. Singleton, term babies born to women with GDM and no other risk factors for hypoglycaemia, were included. Capillary blood glucose (BG) testing and clinical observations for signs of hypoglycaemia during the first 24-h after birth. BG was checked in all babies before the second feed. Subsequent testing occurred if the first result was < 2.0 mmol/L, or clinical suspicion developed for hypoglycaemia. Neonatal hypoglycaemia, defined as either capillary or venous glucose ≤ 2.0 mmol/L and/or clinical signs of neonatal hypoglycaemia requiring oral or intravenous dextrose (lethargy, abnormal feeding behaviour or seizures).

RESULTS

Fifteen of 106 babies developed hypoglycaemia within the first 24-h. Maternal and neonatal characteristics were not predictive. All babies with hypoglycaemia had an initial capillary BG ≤ 2.6 mmol/L (Area under the ROC curve (AUC) 0.96, 95% Confidence Interval (CI) 0.91-1.0). This result was validated on a further 65 babies, of whom 10 developed hypoglycaemia, in the first 24-h of life.

CONCLUSION

Using the 2.6 mmol/L threshold, extended monitoring as an inpatient could have been avoided for 60% of babies in this study. Whilst prospective validation is needed, this approach could help tailor postnatal care plans for babies born to mothers with GDM.

The efficacy of metformin compared with insulin in regulating blood glucose levels during gestational diabetes mellitus: A randomized clinical trial

BACKGROUND

Insulin has been a conventional medication in the treatment of female patients suffering from gestational diabetes mellitus (GDM). However, the need for a large number of insulin injections in these patients causes them a lot of discomforts. Recently, an alternative medication, metformin, has received considerable attention in the treatment of GDM. The aim of this study was to compare the efficacy of metformin and insulin in regulating blood glucose levels and fetal outcomes in GDM.

METHODS

This randomized clinical trial included 286 pregnant women diagnosed with positive GDM at 24-28 weeks of pregnancy. The subjects were randomly divided into two groups of 143 patients, with one group receiving insulin and the other undergoing a treatment plan using metformin. Fasting plasma glucose (FPG), 2-hr plasma glucose (PG) and glycated hemoglobin (HbA1c) were recorded twice a month until delivery. Other variables, including birth delivery method, cause of cesarean section, gestational age at the delivery time, birth trauma, Apgar score, birth weight, admission at neonatal intensive care unit (NICU), and neonatal hypoglycemia were also registered.

RESULTS

Age of mother, body mass index, history of diabetes in the family, previous history of GDM, parity, FPG, 1- and 2-hr PG after meals, and 75-g glucose tolerance test before treatment were not statistically different between the two groups. FPG, PG, and HbA1c did not show significant differences between the two groups after completing the course of treatment. There was also no significant difference between two groups regarding the birth delivery method, the cause of cesarean section, birth trauma, Apgar score, birth weight, admission at NICU, and neonatal hypoglycemia.

CONCLUSION

As mean FPG and 2-hr PG were not significantly different between the two groups, it seems that metformin can be recommended as an effective substitute for insulin in the treatment of GDM. However, there are still some undesirable risk factors with both treatments that may threaten the mother and the newborn.

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.

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.

Metformin in gestational diabetes mellitus: predictors of poor response

OBJECTIVE

Metformin can be regarded as a first-line treatment in gestational diabetes mellitus (GDM) due to its safety and effectiveness. However, a proportion of women do not achieve adequate glycemic control with metformin alone. We aim to identify predictors of this poor response to metformin.

DESIGN AND METHODS

Retrospective multicentre cohort study of women with GDM who started metformin as first-line treatment. The assessed cohort was divided into a metformin group and metformin plus insulin group. Biometric and demographic characteristics, glycemic control data, obstetric, neonatal and postpartum outcomes were compared between groups and analysed in order to identify predictors of poor response to metformin. Data were analysed using STATA, version 13.1.

RESULTS

Of the 388 women enrolled in the study, 135 (34.8%) required additional insulin therapy to achieve the glycemic targets. Higher age (aOR: 1.08 (1.03-1.13), P = 0.003), higher pre-pregnancy body mass index (BMI) (1.06 (1.02-1.10), P = 0.003) and earlier introduction of metformin (0.89 (0.85-0.94), P < 0.001) were independent predictors for insulin supplementation. Regarding all the analysed outcomes, only cesarean delivery rates and postpartum glucose levels were higher in women requiring insulin supplementation.

CONCLUSIONS

Although almost 35% of women did not achieve adequate glycemic control with metformin, insulin supplementation was not associated with poor neonatal outcomes. Higher age, higher pre-pregnancy BMI and earlier introduction of metformin could be used as predictors of poor response to metformin.

Patterns of glucose-lowering therapies and neonatal outcomes in the treatment of gestational diabetes in Canada, 2009-2014

AIM

To examine patterns of use of different glycaemic control agents for treating gestational diabetes mellitus.

METHODS

This was a large, retrospective, population-based cohort study of pregnant women with gestational diabetes from Alberta, Canada. We linked data from the Alberta Vital Statistics - Birth database with administrative claims data. Alberta Vital Statistics - Birth data were used to identify births that occurred between 1 January 2009 and 31 December 2014. We used International Classification of Diseases version 9/10 codes to identify women with gestational diabetes, and we excluded women with pre-existing diabetes.

RESULTS

Our cohort consisted of 16 857 women with gestational diabetes, with a total of 18 761 birth events between 2009 and 2014. Over the study period, the proportion of women with gestational diabetes who were treated with glycaemic control therapies increased from 25.0% to 31.4% (P<0.0001). The number of pregnancies treated with insulin only increased (from 23.6% to 28.3%; P<0.0001), as did the number treated with metformin, +/- insulin (from 1.4% to 3.2%; P<0.0001). Rates of large-for-gestational-age infants were significantly higher among pregnancies treated with insulin only (17%) or metformin (16.5%) than among pregnancies that did not receive any pharmacological treatment (12.8%).

CONCLUSIONS

Our findings show increasing use of insulin and metformin in women with gestational diabetes. Rates of large-for-gestational-age infants were similar among pregnant women receiving either pharmacological treatment, and higher than among pregnant women who did not receive any pharmacological treatment. Future research should explore the long-term outcomes and safety of metformin as an alternative for treating gestational diabetes.

Feto-maternal outcomes and Glycemic control in Metformin versus insulin treated Gestational Diabetics

OBJECTIVE

To evaluate and compare feto-maternal outcomes and glycemic control in metformin versus insulin treated gestational diabetics.

METHODS

The study was conducted in 2010- 2012 as a part of M. Phil at Civil hospital, Lyari General Hospital and Mamji Hospital in Karachi. After written informed consent, 71 GDM diagnosed females with WHO criteria were enrolled. They were divided into two groups. Group-A, 32 females were given oral metformin 500 mg TDS while Group-B, 39 females were given insulin 0.8-0.9 mg/kg/day in two divided doses subcutaneously. Patients were followed till term. Feto-maternal outcomes were evaluated in 25 patients in each group who completed the study.

RESULTS

When groups were compared, newborns in Group-B were significantly more in weight (p=0.01). Significant numbers of babies were delivered after 38 weeks of pregnancy in Group-B (P=0.021). There were two intrauterine deaths and significantly higher HbA1C at term in Group-B. (P=0.03). FBS at term was non-significant (p=0.079) and there was more number of cesarean sections due to feto-maternal disproportion in Group-B (28% vs.2%). Results analyzed for glycemic control before and after the treatment revealed that FBS was statistically less in Group-A (p=0.00) whereas for Group-B the value of FBS and HbA1C was statistically high. (p=0.002 & 0.04 respectively).

CONCLUSION

Metformin has produced better effects on feto-maternal outcomes and glycemic control in comparison to Insulin in GDM.

Efficacy of metformin in improving glycaemic control & perinatal outcome in gestational diabetes mellitus: A non-randomized study

BACKGROUND & OBJECTIVES

Gestational diabetes mellitus (GDM) can cause adverse perinatal outcome if not treated. Although insulin therapy has been the main treatment modality over decades but considering its cost and parenteral mode of administration, it does not seem to be appropriate, especially in low-resource settings. The objective of this study was to evaluate the role of metformin in GDM and know its efficacy as well as adverse effect on foetus and mother.

METHODS

All pregnant women with GDM who were not controlled on medical nutrition therapy and required metformin therapy were included in the study. Careful monitoring of blood sugar was done. Development of any maternal or foetal complications and adverse effect were recorded.

RESULTS

A total of 2797 pregnant women were screened, of whom 233 (8.3%) were found to have GDM. Of the 64 women with GDM (28.7%) who required metformin therapy, majority (93.8%) achieved blood sugar control, whereas three (4.7%) women failed. Caesarean section rate was 54 per cent, and 15.6 per cent neonates were large for gestational age. Only two (3.1%) women had gastrointestinal side effects which were minor and got resolved with time. No case of hypoglycaemia or perinatal mortality was reported.

INTERPRETATION & CONCLUSIONS

Our findings indicate that metformin may be used as a safe and effective oral hypoglycaemic agent in GDM, especially in low-resource settings where cost, storage and compliance are logistic issues. However, long-term follow up studies are needed to solve issues related to its safety in pregnancy.

Effects of Diet and Metformin on placental morphology in Gestational Diabetes Mellitus

Objective:

To evaluate the effects of diet control and Metformin on placental morphology in gestational diabetes mellitus (GDM).

Methods:

After written informed consent 62 GDMs were enrolled. According to WHO criteria, 30 cases of GDMs with blood sugar level <130 mg/dl, were assigned Group B (2000-2500Kcal/day and 30 minute walk thrice weekly were kept on diet control and 32 cases of GDM with blood sugar level >130 mg/dl, assigned Group C were kept on diet with tablet Metformin,(500mg TDS) Finally 25 normal pregnant females were kept in Group A as control. After delivery placentae were preserved and evaluated for morphology.

Results:

Heavy placentae with abundant villous immaturity, chorangiosis and syncytial knots in group B and fibrinoid necrosis and calcification in group C were seen. In group B versus A placental and cord width while in Group C versus A only cord width in gross morphology showed significant results. In group B versus A villous immaturity, chorangiosis, infarction and syncytial knots in light microscopy were present; similarly in B versus C placental width, chorangiosis and syncytial knots showed significant results, while in C versus A results were non-significant.

Conclusion:

Metformin produced beneficial effects on placental morphology being comparable to normal control in contrast to diet group.

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.

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.

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.

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).

Metformin versus insulin treatment in gestational diabetes in pregnancy in a developing country: a randomized control trial

AIM

To compare treatment with metformin alone, metformin plus insulin and insulin alone in women with gestational diabetes (GDM).

METHOD

A total of 150 gestational diabetic patients who fulfilled the eligibility criteria were included in this prospective randomized control open labeled study. A risk factor based screening was done followed by a GCT and then local GTT criteria from antenatal clinics. They were initially divided into two groups with odd numbers assigned to metformin treatment and even numbers to insulin treatment. Metformin and/or insulin treatment was given and target blood sugar levels aimed at FBS ≤ 100 mg/dl and postprandial levels ≤ 126 mg/dl. Supplemental insulin was added to metformin treatment group to maintain the glycemic targets if required. Patients were followed until delivery and maternal fetal outcomes and pharmacotherapeutic characteristics were recorded on a performa.

RESULTS

Less maternal weight gain was found in the metformin treated groups (9.8 ± 1.5 kg [metformin alone] vs. 9.8 ± 1.4 kg [metformin plus insulin] vs. 12.5 ± 1.1 kg [insulin alone] P < 0.000). Preeclampsia was significantly less in metformin treated groups. There were no perinatal deaths in the study. Mean birth weight was significantly less in metformin treated groups (3.4 ± 0.4 kg vs. 3.3 ± 0.5 kg vs. 3.7 ± 0.5 kg P < 0.01). Less neonatal morbidity was observed in metformin groups. 42.7% of patients required supplemental insulin (mean dose of 13.6 ± 2 units) in the metformin group. Mean gestational age at which insulin was added was 31.8 ± 5.9 weeks.

CONCLUSION

Metformin is an effective and cheap treatment option for women with gestational diabetes with or without supplemental insulin.

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

Insulin has been the mainstay of treatment of diabetes during pregnancy for decades. Although glyburide and metformin are classified as category B during pregnancy, recent research has suggested that these oral agents alone or in conjunction with insulin may be safe for the treatment of gestational diabetes (GDM). This paper summarizes the data on the use of glyburide and metformin for treatment of GDM.

Prenatal metformin exposure in a maternal high fat diet mouse model alters the transcriptome and modifies the metabolic responses of the offspring

AIMS

Despite the wide use of metformin in metabolically challenged pregnancies, the long-term effects on the metabolism of the offspring are not known. We studied the long-term effects of prenatal metformin exposure during metabolically challenged pregnancy in mice.

MATERIALS AND METHODS

Female mice were on a high fat diet (HFD) prior to and during the gestation. Metformin was administered during gestation from E0.5 to E17.5. Male and female offspring were weaned to a regular diet (RD) and subjected to HFD at adulthood (10-11 weeks). Body weight and several metabolic parameters (e.g. body composition and glucose tolerance) were measured during the study. Microarray and subsequent pathway analyses on the liver and subcutaneous adipose tissue of the male offspring were performed at postnatal day 4 in a separate experiment.

RESULTS

Prenatal metformin exposure changed the offspring's response to HFD. Metformin exposed offspring gained less body weight and adipose tissue during the HFD phase. Additionally, prenatal metformin exposure prevented HFD-induced impairment in glucose tolerance. Microarray and annotation analyses revealed metformin-induced changes in several metabolic pathways from which electron transport chain (ETC) was prominently affected both in the neonatal liver and adipose tissue.

CONCLUSION

This study shows the beneficial effects of prenatal metformin exposure on the offspring's glucose tolerance and fat mass accumulation during HFD. The transcriptome data obtained at neonatal age indicates major effects on the genes involved in mitochondrial ATP production and adipocyte differentiation suggesting the mechanistic routes to improved metabolic phenotype at adulthood.

Gestational diabetes mellitus management with oral hypoglycemic agents

Oral hypoglycemic agents such as glyburide (second-generation sulfonylurea) and metformin (biguanide) are attractive alternatives to insulin due to lower cost, ease of administration, and better patient adherence. The majority of evidence from retrospective and prospective studies suggests comparable efficacy and safety of oral hypoglycemic agents such as glyburide and metformin as compared to insulin when used in the treatment of women with gestational diabetes mellitus (GDM). Glyburide and metformin have altered pharmacokinetics during pregnancy and both agents cross the placenta. In this article, we review the efficacy, safety, and dosage of oral hypoglycemic agents for the treatment of gestational diabetes mellitus. Additional research is needed to evaluate optimal dosage for glyburide and metformin during pregnancy. Comparative studies evaluating the effects of glyburide and metformin on long-term maternal and fetal outcomes are also needed.

Glucose and metformin modulate human first trimester trophoblast function: a model and potential therapy for diabetes-associated uteroplacental insufficiency

PROBLEM

Diabetes confers an increased risk of preeclampsia, but its pathogenic role in preeclampsia is poorly understood. The objective of this study was to elucidate the effects of excess glucose on trophoblast function and whether any changes could be reversed by metformin.

METHOD OF STUDY

The human first trimester trophoblast cell line (Sw.71) was treated with glucose at 5, 10, 25, and 50 mm, in the presence and absence of metformin. Trophoblast migration was quantified and supernatant cytokine, chemokine, and angiogenic factors measured.

RESULTS

Increasing concentrations of glucose significantly increased trophoblast secretion of the inflammatory cytokines/chemokines: IL-1β, IL-6, IL-8, GRO-α, RANTES, and G-CSF; significantly increased trophoblast secretion of the anti-angiogenic factors sFlt-1 and sEndoglin; and significantly decreased trophoblast migration. Excess glucose-induced trophoblast IL-1β production was inhibited by disabling the Nalp3/ASC inflammasome. Metformin partially reduced the glucose-induced inflammatory response, but had no effect on the anti-angiogenic or antimigratory response.

CONCLUSION

Excess glucose induced a pro-inflammatory, anti-angiogenic, and antimigratory state in first trimester trophoblast cells. Glucose-induced trophoblast IL-1β secretion was mediated by the inflammasome. Glucose-induced inflammation was partially reversed by metformin. These findings demonstrate the pleiotropic effects of hyperglycaemia on the trophoblast, providing potential explanations for the strong link between diabetes and preeclampsia.

Impact of metformin on reproductive tissues: an overview from gametogenesis to gestation

Metformin is an oral anti-hyperglycemic drug that acts as an insulin sensitizer in the treatment of diabetes mellitus type 2. It has also been widely used in the treatment of polycystic ovary syndrome (PCOS) and gestational diabetes. This drug has been shown to activate a protein kinase called 5' AMP-activated protein kinase or AMPK. AMPK is present in many tissues making metformin's effect multi factorial. However as metformin crosses the placenta, its use during pregnancy raises concerns regarding potential adverse effects on the mother and fetus. The majority of reports suggest no significant adverse effects or teratogenicity. However, disconcerting reports of male mouse offspring that were exposed to metformin in utero that present with a reduction in testis size, seminiferous tubule size and in Sertoli cell number suggest that we do not understand the full suite of effects of metformin. In addition, recent molecular evidence is suggesting an epigenetic effect of metformin which could explain some of the long-term effects reported. Nevertheless, the data are still insufficient to completely confirm or disprove negative effects of metformin. The aims of this review are to provide a summary of the safety of metformin in various aspects of sexual reproduction, the use of metformin by gestating mothers, and its possible side-effects on offspring from women who are administered metformin during pregnancy.

Neonatal outcomes in women with gestational diabetes mellitus treated with metformin in compare with insulin: A randomized clinical trial

BACKGROUND

The objective of this study was to compare neonatal outcomes in women with gestational diabetes mellitus (GDM) treated with either metformin or insulin.

MATERIALS AND METHODS

A randomized clinical trial carried out on year 2011 on 109 women with GDM who did not adequately control by dietary measures. They received metformin 500 mg once or twice daily or insulin 0.2 IU/kg/day initially. The dose was titrated to achieve target blood glucose values. Neonatal outcomes such as hypoglycemia, birth weight, Apgar score, umbilical artery pH, and hyperbilirubinemia in the 50 women who remained exclusively on metformin were compared with 50 women who treated with insulin.

RESULTS

Two groups were similar in mean fasting blood sugar (P = 0.7) and postprandial measurements (P = 0.8) throughout GDM treatment. Pregnancy complications or preterm labor were not different significantly between two groups. Considering neonatal outcomes between insulin and metformin groups, such as hypoglycemia (2 [4%] and 0 [0%], respectively), birth weight (3342 ± 506 mg and 3176 ± 438 mg, respectively), 5(th) min Apgar score <7 (no one in either group), umbilical artery pH <7.05 (no one in either group) and hyperbilirubinemia (1 [2%] and 0 [0%], respectively), no significant statistical differences were seen.

CONCLUSION

Based on these preliminary data, considering neonatal outcomes, metformin appears to be a safe as insulin in the treatment of GDM.

Metformin safety in the management of gestational diabetes

OBJECTIVE

The use of metformin in pregnant women is still controversial, despite the increasing reports on metformin's safety and effectiveness. We aimed to evaluate the maternal and neonatal safety of metformin in subjects with gestational diabetes mellitus (GDM).

METHODS

We retrospectively reviewed the clinical records of 186 pregnancies complicated with GDM surveilled at Hospital de Santa Maria, Lisboa, between 2011 and 2012. The maternal and neonatal outcomes of 32 females who took metformin during pregnancy were compared with 121 females controlled with diet and 33 insulin-treated females.

RESULTS

Of the 186 GDM subjects, 32 (17.2%) received metformin during pregnancy. No statistical differences between the diet and metformin groups were found with regard to the rates of abortion, prematurity, preeclampsia, macrosomy, small-for-gestational-age (SGA) or large-for-gestational-age (LGA) newborns, cesarean deliveries, neonatal intensive care unit (NICU) admissions, and birth malformations or neonatal injuries. Similarly, there were no differences between the metformin and insulin groups with regard to the referred outcomes. No abortions or perinatal deaths were recorded in the metformin group. Ten out of 32 metformin patients required additional insulin.

CONCLUSION

This retrospective study suggests that metformin is a safe alternative or additional treatment to insulin in females with GDM. Metformin was not associated with a higher risk of maternal or neonatal complications when compared to the insulin or diet groups.

Metformin: Current knowledge

Diabetes mellitus is a group of metabolic disorders in which the blood glucose is higher than normal levels, due to insufficiency of insulin release or improper response of cells to insulin, resulting in high blood pressure. The resultant hyperglycemia produces sever complications. Metformin drug has been shown to prevent diabetes in people who are at high risk and decrease most of the diabetic complications. Recent reports on metformin, not only indicate some implications such as renoprotective properties have been suggested for metformin, but some reports indicate its adverse effects as well that are negligible when its benefits are brought into account. We aimed here to review the new implications of metformin and discuss about the concerns in the use of metformin, referring to the recently published papers.

First-trimester exposure to metformin and risk of birth defects: a systematic review and meta-analysis

BACKGROUND

Metformin is generally considered a non-teratogenic drug; however, only a few studies specifically designed to assess the rate of congenital anomalies after metformin use have been published in the literature. The objects of the present study were to review all of the prospective and retrospective studies reporting on women treated with metformin at least during the first trimester of their pregnancy and to estimate the overall rate of major birth defects.

METHODS

Databases were searched for English language articles until December 2013. Inclusion criteria for the meta-analysis were: a case group of women with PCOS or pre-pregnancy type 2 diabetes and first-trimester exposure to metformin; a disease-matched control group which was not exposed to metformin or other oral anti-diabetic agents; and a list of the major anomalies in both the study and the control groups. A random effects model was used for the meta-analysis of data, using odds ratios. Studies not fulfilling the inclusion criteria for the meta-analysis but reporting relevant data on major malformations in women diagnosed with PCOS were then used to estimate the overall birth defects rate.

RESULTS

Meta-analysis of nine controlled studies with women affected by PCOS detected that the rate of major birth defects in the metformin-exposed group was not statistically increased compared with the disease-matched control group and that there was no significant heterogeneity among the studies. The metformin-exposed sample was composed of 351 pregnancies and the OR of major birth defects was 0.86 (95% confidence interval: 0.18-4.08; Pheterogeneity = 0.71). By evaluating all of the non-overlapping PCOS studies reported in the literature, even those without an appropriate control group, the overall rate of major anomalies was 0.6% in the sample of 517 women who discontinued the therapy upon conception or confirmation of pregnancy and 0.5% in the sample of 634 women who were treated with metformin throughout the first trimester of their pregnancy. Regarding type 2 diabetic women, we did not identify a sufficient number of studies with metformin exposure during the first trimester to proceed with the meta-analysis.

CONCLUSIONS

There is currently no evidence that metformin is associated with an increased risk of major birth defects in women affected by PCOS and treated during the first trimester. However larger ad hoc studies are warranted in order to definitely confirm the safety and efficacy of this drug in pregnancy.

The use of oral hypoglycaemic agents in pregnancy

While insulin has been the treatment of choice when lifestyle measures do not maintain glycaemic control during pregnancy, recent studies have suggested that certain oral hypoglycaemic agents may be safe and acceptable alternatives. With the exception of metformin and glibenclamide (glyburide), there are insufficient data to recommend treatment with any other oral hypoglycaemic agent during pregnancy. There are no serious safety concerns with metformin, despite it crossing the placenta. When used in the first trimester, there is no increase in congenital abnormalities and there appears to be a reduction in miscarriage, pre-eclampsia and subsequent gestational diabetes. Studies of the use of metformin in gestational diabetes show at least equivalent neonatal outcomes, while reporting reductions in neonatal hypoglycaemia, maternal hypoglycaemia and weight gain and improved treatment satisfaction. Glibenclamide effectively lowers blood glucose in women with gestational diabetes, possibly with a lower treatment failure rate than metformin. Although generally well tolerated, some studies have reported higher rates of pre-eclampsia, neonatal jaundice, longer stay in the neonatal care unit, macrosomia and neonatal hypoglycaemia. There is a paucity of long-term follow-up data on children exposed to oral agents in utero. The American College of Obstetrics and Gynecology and the UK National Institute of Health and Care Excellence (NICE) have recommended that either metformin or glibenclamide can be used to treat gestational diabetes. Metformin is also recommended for use in the pre-conception period by NICE. By contrast, the American Diabetes Association recommends that both drugs should only be used during pregnancy in the context of clinical trials.

Efficacy and safety of metformin during pregnancy in women with gestational diabetes mellitus or polycystic ovary syndrome: a systematic review

BACKGROUND

Metformin is an effective oral anti-hyperglycemic agent that is widely used to manage diabetes mellitus type 2 in the general population and more recently, in pregnancy. However, as metformin crosses the placenta, its use during pregnancy raises concerns regarding potential adverse effects on the mother and fetus.

OBJECTIVE

(i) To provide background for the use of metformin during pregnancy through a narrative review and (ii) to critically appraise the published evidence on the efficacy and safety of using metformin during pregnancy through a systematic review.

RESULTS

Metformin appears to be effective and safe for the treatment of gestational diabetes mellitus (GDM), particularly for overweight or obese women. However, patients with multiple risk factors for insulin resistance may not meet their treatment goals with metformin alone and may require supplementary insulin. Evidence suggests that there are potential advantages for the use of metformin over insulin in GDM with respect to maternal weight gain and neonatal outcomes. Furthermore, patients are more accepting of metformin than insulin. The use of metformin throughout pregnancy in women with polycystic ovary syndrome reduces the rates of early pregnancy loss and preterm labor and protects against fetal growth restriction. There have been no demonstrable teratogenic effects, intra-uterine deaths or developmental delays with the use of metformin.

CONCLUSIONS

The publications reviewed in this paper support the efficacy and safety of metformin during pregnancy with respect to immediate pregnancy outcomes. Because there are no guidelines for the continuous use of metformin in pregnancy, the duration of treatment is based on clinical judgment and experience on a case-by-case basis.

Randomized trial of metformin vs insulin in the management of gestational diabetes

OBJECTIVE

To evaluate glycemic control in women receiving metformin or insulin for gestational diabetes, and to identify factors predicting the need for supplemental insulin in women initially treated with metformin.

STUDY DESIGN

Women with gestational diabetes who failed to achieve glycemic control with diet and exercise were randomized to receive metformin (n = 47) or insulin (n = 47). Criteria for inclusion were singleton pregnancy, diet, and exercise for a minimum period of 1 week without satisfactory glycemic control, absence of risk factors for lactic acidosis, and absence of anatomic and/or chromosome anomalies of the conceptus. Patients who were lost to prenatal follow-up were excluded.

RESULTS

Comparison of mean pretreatment glucose levels showed no significant difference between groups (P = .790). After introduction of the drug, lower mean glucose levels were observed in the metformin group (P = .020), mainly because of lower levels after dinner (P = .042). Women using metformin presented less weight gain (P = .002) and a lower frequency of neonatal hypoglycemia (P = .032). Twelve women in the metformin group (26.08%) required supplemental insulin for glycemic control. Early gestational age at diagnosis (odds ratio, 0.71; 95% confidence interval, 0.52-0.97; P = .032) and mean pretreatment glucose level (odds ratio, 1.061; 95% confidence interval, 1.001-1.124; P = .046) were identified as predictors of the need for insulin.

CONCLUSION

Metformin was found to provide adequate glycemic control with lower mean glucose levels throughout the day, less weight gain and a lower frequency of neonatal hypoglycemia. Logistic regression analysis showed that gestational age at diagnosis and mean pretreatment glucose level were predictors of the need for supplemental insulin therapy in women initially treated with metformin.

Metformin vs insulin in the management of gestational diabetes: a meta-analysis

BACKGROUND

Nowadays, there have been increasing studies comparing metformin with insulin. But the use of metformin in pregnant women is still controversial, therefore, we aim to examine the efficiency and safety of metformin by conducting a meta-analysis of randomized controlled trials (RCTs) comparing the effects of metformin with insulin on glycemic control, maternal and neonatal outcomes in gestational diabetes mellitus (GDM).

METHODS

We used the key words "gestational diabetes" in combination with "metformin" and searched the databases including Pubmed, the Cochrane Library, Web of knowledge, and Clinical Trial Registries. A random-effects model was used to compute the summary risk estimates.

RESULTS

Meta-analysis of 5 RCTs involving 1270 participants detected that average weight gains after enrollment were much lower in the metformin group (n = 1006, P = 0.003, SMD = -0.47, 95%CI [-0.77 to -0.16]); average gestational ages at delivery were significantly lower in the metformin group (n = 1270, P = 0.02, SMD = -0.14, 95%CI [-0.25 to -0.03]); incidence of preterm birth was significantly more in metformin group (n = 1110, P = 0.01, OR = 1.74, 95%CI [1.13 to 2.68]); the incidence of pregnancy induced hypertension was significantly less in the metformin group (n = 1110, P = 0.02, OR = 0.52, 95%CI [0.30 to 0.90]). The fasting blood sugar levels of OGTT were significantly lower in the metformin only group than in the supplemental insulin group (n = 478, P = 0.0006, SMD = -0.83, 95%CI [-1.31 to -0.36]).

CONCLUSIONS

Metformin is comparable with insulin in glycemic control and neonatal outcomes. It might be more suitable for women with mild GDM. This meta-analysis also provides some significant benefits and risks of the use of metformin in GDM and help to inform further development of management guidelines.

Effect of type 2 diabetes mellitus on the pharmacokinetics of metformin in obese pregnant women

BACKGROUND AND OBJECTIVE

The use of metformin throughout gestation by women with polycystic ovary syndrome (PCOS) and type 2 diabetes mellitus (T2DM) significantly reduces the number of first-trimester spontaneous abortions and the rate of occurrence of gestational diabetes and hypertensive syndromes. Metformin is taken up into renal tubular cells by organic cation transport 2 (OCT2) and eliminated unchanged into the urine. The objective of this study was to analyse the influence of T2DM on the pharmacokinetics of metformin in obese pregnant women and in a control group of non-diabetic obese pregnant women with PCOS.

METHODS

Eight non-diabetic obese pregnant women with PCOS and nine obese pregnant women with T2DM taking oral metformin 850 mg every 12 h were evaluated throughout gestation. Serial blood samples were collected over a 12-h period during the third trimester of pregnancy. Steady-state plasma concentrations of metformin were determined by high-performance liquid chromatography with a UV detector. The pharmacokinetic results of the two groups, reported as median and 25th and 75th percentile, were compared statistically using the Mann-Whitney test, with the level of significance set at p < 0.05.

RESULTS

The pharmacokinetic parameters detected for PCOS versus T2DM patients, reported as median, were, respectively: elimination half-life 3.75 versus 4.00 h; time to maximum concentration 2.00 versus 3.00 h; maximum concentration 1.42 versus 1.21 μg/mL; mean concentration 0.53 versus 0.56 μg/mL; area under the plasma concentration-time curve from time zero to 12 h 6.42 versus 6.73 μg·h/mL; apparent total oral clearance 105.39 versus 98.38 L/h; apparent volume of distribution after oral administration 550.51 versus 490.98 L; and fluctuation (maximum-minimum concentration variation) of 179.56 versus 181.73 %. No significant differences in pharmacokinetic parameters were observed between the groups.

CONCLUSION

T2DM in the presence of insulin use does not influence the pharmacokinetics of metformin in pregnant patients, demonstrating the absence of a need to increase the dose, and consequently does not influence the OCT2-mediated transport in pregnant women with PCOS.

Metformin vs. insulin in gestational diabetes. A randomized study characterizing metformin patients needing additional insulin

AIMS

We compared metformin with insulin as treatment of gestational diabetes mellitus (GDM). Furthermore, we aimed to characterize metformin-treated patients needing additional insulin to achieve prespecified glucose targets.

METHODS

We conducted a single centre randomized controlled study with non-inferiority design comparing metformin and insulin in the treatment of 217 GDM patients having birth weight as primary outcome variable.

RESULTS

There were no significant differences in mean birth weight expressed in grams [+15 (90% confidence interval (CI): -121 to 89)] or SD units [+0.04 (90% CI: -0.27 to 0.18)] between the metformin and insulin groups. There were no significant differences in neonatal or maternal data between the groups. Only 23 (20.9%) of the 110 patients in the metformin group needed additional insulin. Compared with the patients on metformin only, those needing additional insulin were older (p = 0.04), their oral glucose tolerance test had been performed earlier and diabetes therapy started earlier in gestation (p = 0.01 and p = 0.004, respectively). The risk for additional insulin was 4.6-fold in women with baseline serum fructosamine concentration above median compared with those below median.

CONCLUSIONS

Metformin is an effective alternative to insulin in the treatment of GDM patients. Serum fructosamine may help in predicting the adequacy of metformin treatment alone.

Comparison of newborn outcomes in women with gestational diabetes mellitus treated with metformin or insulin: a randomised blinded trial

BACKGROUND

Few studies have been done on the use of metformin in pregnancy and their results were not similar, therefore this research is performed to compare neonatal outcomes of metformin and insulin in the treatment of gestational diabetes.

METHODS

In this prospective randomized trial, 200 pregnant women within their 24(th) to 34(th) weeks of gestation with gestational diabetes, single fetus pregnancy, and in need of hyperglycemia treatment were entered and grouped as either metformin or insulin. Data related to maternal and neonatal outcomes were recorded and analyzed.

RESULTS

Considering data recorded of HbA1c at the beginning of pregnancy, pregnancy induced hypertension, preeclampsia, birth weight, dystocia, first and 5(th) min APGAR, neonatal sepsis, rout of delivery, liver function tests of neonate, hypoglycemia, anomaly, and still birth, there were no significant statistical differences between groups. The end pregnancy HbA1c, maternal weight gain during pregnancy, preterm labor, neonatal jaundice, respiratory distress and hospitalization of infants were higher in insulin group.

CONCLUSIONS

Considering data from this study, metformin is efficient to control hyperglycemia in pregnancy. It is suggested performing more studies to evaluate long term side effects of metformin in pregnancy with higher sample size and longer follow-up of newborns.

Prenatal metformin exposure in mice programs the metabolic phenotype of the offspring during a high fat diet at adulthood

AIMS

The antidiabetic drug metformin is currently used prior and during pregnancy for polycystic ovary syndrome, as well as during gestational diabetes mellitus. We investigated the effects of prenatal metformin exposure on the metabolic phenotype of the offspring during adulthood in mice.

METHODS

Metformin (300 mg/kg) or vehicle was administered orally to dams on regular diet from the embryonic day E0.5 to E17.5. Gene expression profiles in liver and brain were analysed from 4-day old offspring by microarray. Body weight development and several metabolic parameters of offspring were monitored both during regular diet (RD-phase) and high fat diet (HFD-phase). At the end of the study, two doses of metformin or vehicle were given acutely to mice at the age of 20 weeks, and Insig-1 and GLUT4 mRNA expressions in liver and fat tissue were analysed using qRT-PCR.

RESULTS

Metformin exposed fetuses were lighter at E18.5. There was no effect of metformin on the maternal body weight development or food intake. Metformin exposed offspring gained more body weight and mesenteric fat during the HFD-phase. The male offspring also had impaired glucose tolerance and elevated fasting glucose during the HFD-phase. Moreover, the expression of GLUT4 mRNA was down-regulated in epididymal fat in male offspring prenatally exposed to metformin. Based on the microarray and subsequent qRT-PCR analyses, the expression of Insig-1 was changed in the liver of neonatal mice exposed to metformin prenatally. Furthermore, metformin up-regulated the expression of Insig-1 later in development. Gene set enrichment analysis based on preliminary microarray data identified several differentially enriched pathways both in control and metformin exposed mice.

CONCLUSIONS

The present study shows that prenatal metformin exposure causes long-term programming effects on the metabolic phenotype during high fat diet in mice. This should be taken into consideration when using metformin as a therapeutic agent during pregnancy.

Fasting blood glucose predicts response to extended-release metformin in gestational diabetes mellitus

BACKGROUND

Metformin is increasingly accepted as an alternative to insulin therapy in gestational diabetes mellitus (GDM). The Metformin in Gestational Diabetes (MiG) trial reported similar pregnancy outcomes for metformin versus insulin; however, supplemental insulin was required in 46% of women on metformin.

AIMS

We aimed to identify predictors of response to metformin monotherapy in women with GDM attending a general hospital antenatal clinic.

METHODS

We offered extended-release metformin to women diagnosed with GDM (ADIPS 1998 criteria) at ≥24 weeks of gestation. If glucose targets were not achieved (≤5.0 mmol/L fasting, ≤6.7 mmol/L two-h post-meal), women were changed to insulin. We carried out an audit to determine characteristics of metformin responders versus nonresponders.

RESULTS

Twenty-five women chose initial metformin therapy; 16 (64%) achieved satisfactory glycaemic control (responders). Nine women (36%) were changed to insulin: seven due to inadequate control (nonresponders) and two had metformin intolerance. Fasting glucose at oral glucose tolerance test (OGTT) was significantly lower in metformin responders versus nonresponders; two-h glucose and BMI did not differ. Ninety-three percent of women with fasting glucose ≤5.2 mmol/L responded to metformin: conversely, at fasting glucose >5.2 mmol/L, 33% responded (P = 0.005). Neonatal outcomes were similar in metformin responders and nonresponders, women who chose initial insulin therapy (n = 25), or were diet-controlled (n = 21).

CONCLUSIONS

In women with GDM, fasting glucose on OGTT predicted response to metformin: at fasting glucose ≤5.2 mmol/L, the probability of response was 93%. Antenatal clinics should determine locally relevant predictors of response to metformin in women with GDM.