Pregnancy outcomes in women with gestational diabetes treated with metformin or insulin: a case-control study

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.

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.

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.

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.

Estradiol Binds to Insulin and Insulin Receptor Decreasing Insulin Binding in vitro

RATIONALE

Insulin (INS) resistance associated with hyperestrogenemias occurs in gestational diabetes mellitus, polycystic ovary syndrome, ovarian hyperstimulation syndrome, estrogen therapies, metabolic syndrome, and obesity. The mechanism by which INS and estrogen interact is unknown. We hypothesize that estrogen binds directly to INS and the insulin receptor (IR) producing INS resistance.

OBJECTIVES

To determine the binding constants of steroid hormones to INS, the IR, and INS-like peptides derived from the IR; and to investigate the effect of estrogens on the binding of INS to its receptor.

METHODS

Ultraviolet spectroscopy, capillary electrophoresis, and NMR demonstrated estrogen binding to INS and its receptor. Horse-radish peroxidase-linked INS was used in an ELISA-like procedure to measure the effect of estradiol on binding of INS to its receptor.

MEASUREMENTS

Binding constants for estrogens to INS and the IR were determined by concentration-dependent spectral shifts. The effect of estradiol on INS binding to its receptor was determined by shifts in the INS binding curve.

MAIN RESULTS

Estradiol bound to INS with a K d of 12 × 10(-9) M and to the IR with a K d of 24 × 10(-9) M, while other hormones had significantly less affinity. Twenty-two nanomolars of estradiol shifted the binding curve of INS to its receptor 0.8 log units to the right.

CONCLUSION

Estradiol concentrations in hyperestrogenemic syndromes may interfere with INS binding to its receptor producing significant INS resistance.

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.

The importance of visceral fat mass in obese pregnant women and relation with pregnancy outcomes

BACKGROUND

Maternal obesity is a well established risk factor for gestational diabetes but it is not known if the pattern of maternal fat distribution predicts adverse pregnancy outcomes.

METHODS

Body composition was assessed by bioimpedance using Inbody 720® in 302 consecutive obese pregnant women attending a weight management clinic. The relation of visceral fat mass and total percentage body fat with the development of gestational diabetes and perinatal outcomes was evaluated.

RESULTS

Women developing gestational diabetes (Group 1; n = 72) were older, had higher body mass indices and greater central obesity (waist:hip ratio, visceral fat mass) compared with those remaining normoglycaemic. Visceral fat mass, but not percentage body fat, correlated with fasting glucose in all patients (r = 0.2, p < 0.001) and particularly those in Group 1 (r = 0.35, p = 0.002). Visceral fat mass, but not percentage body fat, also correlated strongly with glycaemia, particularly in Group 1 (r = 0.47, p < 0.0001). Visceral fat mass also showed a weak but significant correlation with baby weight (r = 0.17, p = 0.01).

DISCUSSION

Central obesity, as assessed by early pregnancy waist:hip ratio and particularly by visceral fat mass, is a predictor of gestational diabetes in addition to classical risk factors and may help identify those obese patients at increased risk of complications.

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.

Maternal and neonatal circulating markers of metabolic and cardiovascular risk in the metformin in gestational diabetes (MiG) trial: responses to maternal metformin versus insulin treatment

OBJECTIVE

This study was designed to compare glucose, lipids, and C-reactive protein (CRP) in women with gestational diabetes mellitus treated with metformin or insulin and in cord plasma of their offspring and to examine how these markers relate to infant size at birth.

RESEARCH DESIGN AND METHODS

Women with gestational diabetes mellitus were randomly assigned to metformin or insulin in the Metformin in Gestational Diabetes trial. Fasting maternal plasma glucose, lipids, and CRP were measured at randomization, 36 weeks' gestation, and 6-8 weeks postpartum as well as in cord plasma. Women with available cord blood samples (metformin n = 236, insulin n = 242) were included.

RESULTS

Maternal plasma triglycerides increased more from randomization to 36 weeks' gestation in women treated with metformin (21.93%) versus insulin (9.69%, P < 0.001). Maternal and cord plasma lipids, CRP, and neonatal anthropometry did not differ between treatments. In logistic regression analyses adjusted for confounders, the strongest associations with birth weight >90th centile were maternal triglycerides and measures of glucose control at 36 weeks.

CONCLUSIONS

There were few differences in circulating maternal and neonatal markers of metabolic status and no differences in measures of anthropometry between the offspring of women treated with metformin and the offspring of women treated with insulin. There may be subtle effects of metformin on maternal lipid function, but the findings suggest that treating gestational diabetes mellitus with metformin does not adversely affect lipids or CRP in cord plasma or neonatal anthropometric measures.

Incidence of adverse outcomes associated with gestational diabetes mellitus in low- and middle-income countries

BACKGROUND

The contribution of medical conditions such as diabetes mellitus to maternal and neonatal ill-health in low- and middle-income countries is not well documented.

OBJECTIVES

To ascertain the incidence of adverse outcomes associated with gestational diabetes mellitus (GDM) in these countries.

SEARCH STRATEGY

Electronic databases were searched between 1990 and 2011.

SELECTION CRITERIA

Observational, experimental, and quasi-experimental studies reporting adverse outcomes associated with GDM in mothers and their infants in low- and middle-income countries were included.

DATA COLLECTION AND ANALYSIS

Titles and abstracts were screened, and full-text articles were independently assessed by at least 2 reviewers. Characteristics of studies were tabulated and quality assessment performed. Median and interquartile range (IQR) were computed for each adverse outcome.

MAIN RESULTS

25 articles were included from an initial 1282 citations. High median incidences of cesarean (43.8%; IQR, 34.9%-65.9%), neonatal jaundice (17.1%; IQR, 8.5%-22.9%), and macrosomia (17.0%; IQR, 8.3%-32.5%) were reported in women with GDM.

CONCLUSIONS

The high incidence of some complications of GDM is a concern and may indicate poorer care for women with GDM in low-resource settings. The wide IQRs found indicate uncertainty about the burden of GDM in these settings.

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.

Metformin compared with insulin in the management of gestational diabetes mellitus: a randomized clinical trial

AIMS

To evaluate the effect of metformin and insulin in glycemic control and compare pregnancy outcome in women with gestational diabetes mellitus (GDM).

METHODS

This randomized controlled trial was conducted in GDM women with singleton pregnancy and gestational age between 20 and 34 weeks who did not achieve glycemic control on diet were assigned randomly to receive either metformin (n=80) or insulin (n=80). The primary outcomes were maternal glycemic control and birth weight. The secondary outcomes were neonatal and obstetric complications.

RESULTS

Two groups were comparable regarding the maternal characteristics. Two groups were similar in mean FBS (P=0.68) and postprandial measurements (P=0.87) throughout GDM treatment. The neonates of metformin group had less rate of birth weight centile >90 than insulin group (RR: 0.5, 95% CI: 0.3-0.9, P=0.012). Maternal weight gain was reduced in the metformin group (P<0.001). Two groups were comparable according to neonatal and obstetric complications (P>0.05). In metformin group 14% of women needed to supplemental insulin to achieve euglycemia.

CONCLUSION

Metformin is an effective and safe alternative treatment to insulin for women with GDM. This study does not show significant risk of maternal or neonatal adverse outcome with the use of metformin.

Effects of metformin use in pregnant patients with polycystic ovary syndrome

Use of metformin throughout pregnancy in women with polycystic ovary syndrome (PCOS) has shown to reduce the rates of early pregnancy loss, preterm labor, and prevention of fetal growth restriction. Metformin has been shown to have encouraging effects on several metabolic aspects of polycystic ovarian syndrome, such as insulin sensitivity, plasma glucose concentration and lipid profile and since women with PCOS are more likely than healthy women to suffer from pregnancy-related problems like early pregnancy loss, gestational diabetes mellitus and hypertensive states in pregnancy, the use of metformin therapy in these patients throughout pregnancy may have beneficial effects on early pregnancy loss and development of gestational diabetes.

Pregnancy outcomes after metformin treatment for gestational diabetes: a case-control study

BACKGROUND

There is increasing evidence that metformin is safe and effective in the treatment of gestational diabetes (GDM), although it has not yet been widely accepted for routine practice. We compared pregnancy outcomes in women with gestational GDM treated with metformin or dietary measures alone.

METHODS

Women with GDM (324) not adequately controlled by diet received metformin according to protocol based on their home glucose results. Pregnancy outcomes in these women were compared with 175 GDM women treated with diet alone and matched for age and ethnicity.

RESULTS

The percentage of macrosomic babies (birth weight [BW] centile >90th centile) and small for gestational age (SGA) (BW <10th centile) in the metformin group was significantly reduced compared with the diet group (12.7% versus 20%; P < 0.05 [macrosomia]; 7.7% versus 14.3% [SGA] P < 0.05).

CONCLUSIONS

Metformin treatment had a favourable impact on the rates of macrosomia and SGA despite more severe glucose intolerance at baseline.

Cellular and molecular mechanisms of metformin: an overview

Considerable efforts have been made since the 1950s to better understand the cellular and molecular mechanisms of action of metformin, a potent antihyperglycaemic agent now recommended as the first-line oral therapy for T2D (Type 2 diabetes). The main effect of this drug from the biguanide family is to acutely decrease hepatic glucose production, mostly through a mild and transient inhibition of the mitochondrial respiratory chain complex I. In addition, the resulting decrease in hepatic energy status activates AMPK (AMP-activated protein kinase), a cellular metabolic sensor, providing a generally accepted mechanism for the action of metformin on hepatic gluconeogenesis. The demonstration that respiratory chain complex I, but not AMPK, is the primary target of metformin was recently strengthened by showing that the metabolic effect of the drug is preserved in liver-specific AMPK-deficient mice. Beyond its effect on glucose metabolism, metformin has been reported to restore ovarian function in PCOS (polycystic ovary syndrome), reduce fatty liver, and to lower microvascular and macrovascular complications associated with T2D. Its use has also recently been suggested as an adjuvant treatment for cancer or gestational diabetes and for the prevention in pre-diabetic populations. These emerging new therapeutic areas for metformin will be reviewed together with recent findings from pharmacogenetic studies linking genetic variations to drug response, a promising new step towards personalized medicine in the treatment of T2D.

Introduction of metformin for gestational diabetes mellitus in clinical practice: Has it had an impact?

OBJECTIVE

The aim of the study was to compare maternal and neonatal outcomes in women with gestational diabetes mellitus (GDM) treated with metformin in addition to the dietary and lifestyle advice versus those treated traditionally with dietary and lifestyle advice only.

STUDY DESIGN

A retrospective study of singleton pregnancies in women with GDM delivered between January 2008 to June 2010 (n=592) at the Jessop Wing, Royal Hallamshre Hospital, UK. Introduction of metformin in August 2008 led to two comparable groups, those women receiving metformin, lifestyle advice (including dietary advice) ± supplementary insulin and those women receiving lifestyle advice (including dietary advice) ± supplementary insulin. Two hundred and ninety three women were treated with metformin and lifestyle advice and remaining 299 with lifestyle advice only. Supplementary insulin was used in both the groups if needed. Outcomes were analyzed using the chi-squared and t-tests.

RESULTS

There were no significant differences in baseline maternal characteristics between the two groups. Metformin was tolerated throughout the pregnancy by 90% of the women in the metformin+lifestyle advice group. Supplementary insulin was required by 21% in the metformin+lifestyle advice group compared to 37% in the lifestyle advice group (OR 0.46; 95% CI 0.32-0.66). Women in the metformin group had a significantly lower incidence of macrosomia (birth weight>4kg) (8.2% vs. 14.3% (OR 0.56; 95% CI 0.33-0.99)), as well as birth weight >90th centile (14.8% vs. 23.7% (OR 0.56; 95% CI 0.37-0.85)). There were no significant differences in maternal outcome measures between the groups. No serious maternal or neonatal adverse events were observed with the use of metformin.

CONCLUSION

Metformin is safe and effective in the treatment of GDM in our experience. It is well tolerated and reduces the requirement for supplementary insulin. Women treated with metformin had a significantly lower incidence of macrosomic and large for gestational age neonates as well as a reduced caesarean section rate.

Metformin for gestational diabetes in routine clinical practice

AIMS

To compare maternal and neonatal outcomes in women with gestational diabetes treated with diet, metformin and/or insulin in routine clinical practice in a single centre.

METHODS

We analysed prospectively collected data from the National Women's Health database for all women with gestational diabetes who delivered between January 2007 and December 2009. Since June 2007, women requiring medication have been given a choice of either metformin or insulin treatment, except women with a fetal abdominal circumference less than the 10th percentile, who were not offered metformin.

RESULTS

There were 1269 women with gestational diabetes; treatment was diet in 371, insulin in 399 and metformin in 465 (249 metformin alone, 216 metformin and insulin). Women treated with metformin and/or insulin had significantly higher BMIs compared with those in the diet group (P < 0.001) and had a higher fasting glucose at diagnosis (p < 0.001). Women treated with insulin had higher rates of Caesarean delivery (45.6% insulin, 37% metformin, 34% diet, P = 0.02) than women treated with metformin or diet. They also had higher rates of preterm births (19.2% insulin, 12.5% metformin, 12.1% diet, P = 0.005), customized large-for-gestational-age infants (18.5% insulin, 12.5% metformin, 12.4% diet, P = 0.02), neonatal admissions (18.7% insulin, 12.7% metformin, 14.0% diet, P = 0.04) and neonatal intravenous dextrose use (11.1% insulin, 5.1% metformin, 7.4% diet, P = 0.004). Neonatal outcomes were similar between diet- and metformin-treated women.

CONCLUSIONS

In routine practice, use of metformin in gestational diabetes was associated with fewer adverse outcomes compared with insulin, but baseline differences between treatment groups may have contributed to this.

Diabetes in pregnancy may differentially affect neonatal outcomes for twins and singletons

AIM

We tested the hypothesis that diabetes in pregnancy may differentially affect neonatal outcomes in twin vs. singleton pregnancies.

METHODS

In a retrospective cohort analysis of twins (n = 422 068) and singletons (n = 14 298 367) born in the USA from 1998 to 2001, we evaluated the adjusted odds ratios of adverse neonatal outcomes comparing diabetic vs. non-diabetic pregnancies, controlling for maternal characteristics. Primary outcomes include macrosomia (birthweight for gestational age > 90th percentile), congenital anomalies, low 5-min Apgar score (< 4) and neonatal death.

RESULTS

Diabetes in pregnancy was associated with a similarly increased risk of congenital anomalies (adjusted odds ratios 1.52 vs. 1.59) and smaller increased risks of preterm birth (adjusted odds ratios 1.27 vs. 1.49) and macrosomia (adjusted odds ratios 1.38 vs. 2.03) in twins vs. singletons, but reduced risks of low 5-min Apgar score (adjusted odds ratio 0.74) and neonatal death (adjusted odds ratio 0.76) in twins but not singletons.

CONCLUSIONS

Diabetes in pregnancy may differentially affect neonatal outcomes in twins and singletons, indicating a need for further studies to differentiate the effects by clinical subtypes of diabetes in pregnancy, and to consider/evaluate differential clinical management protocols of diabetes in multiple vs. singleton pregnancies.

Insulin resistance and the long-term consequences of polycystic ovary syndrome

In a significant number of women with the polycystic ovary syndrome there is impaired insulin metabolism with hypersecretion of insulin. Insulin resistance is defined as a diminution in the glucose response to a given amount of insulin. Insulin resistance has been implicated in the pathogenesis of many aspects of the syndrome. Hyperinsulinaemia leads to increased production of androgens resulting in anovulatory infertility. Women and particularly obese women with insulin resistance and the polycystic ovary syndrome have an increased risk of developing gestational diabetes and also type 2 diabetes and cardiovascular disease in later life. The women should be counselled about long-term health risks, and obese women with the polycystic ovary syndrome should be periodically screened. Lifestyle modification to reduce weight in obese women and treatment with insulin-sensitising drugs such as metformin in women with glucose intolerance result in the improvement of some metabolic abnormalities and hyperandrogenic disorders with the consequent restoration of normal menstrual and ovulatory function in a significant number of women with polycystic ovaries.

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

OBJECTIVE

To examine if oral metformin is as effective as insulin in the prevention of fetal macrosomy in pregnancies complicated with gestational diabetes mellitus (GDM).

DESIGN

Open-label prospective randomised controlled study.

SETTING

Maternity outpatient clinics in a secondary and tertiary level hospital in Finland.

SAMPLE

One hundred women with GDM who did not attain euglycaemia with diet.

METHODS

Women were randomised to therapy with insulin (n = 50) or oral metformin (n = 50).

MAIN OUTCOME MEASURES

Incidence of large-for-gestational-age (LGA) infants and neonatal morbidity.

RESULTS

There were no statistically significant differences in the incidence of LGA (8.5 versus 10.0%, P = 0.97), mean birthweight, mean cord artery pH or neonatal morbidity between the insulin and metformin groups. Fifteen (31.9%) of the 47 women randomised to metformin needed supplemental insulin. They were more obese (with a body mass index of 36 versus 30 kg/m(2), P = 0.002), had higher fasting blood glucose levels in an oral glucose tolerance test (6.1 versus 5.0 mmol/l, P = 0.001) and needed medical treatment for GDM earlier (26 versus 31 gestational weeks, P = 0.002) than women who were normoglycemic with metformin. There was a tendency to a higher rate of caesarean sections in the metformin group than in the insulin group (RR 1.9; 95% CI 0.99-3.71).

CONCLUSIONS

Metformin seems to be suitable for the prevention of fetal macrosomy, especially in lean or moderately overweight women developing GDM in late gestation. Women with considerable obesity, high fasting blood glucose and an early need for pharmacological treatment may be more suitable for insulin therapy.

Metformin treatment for Type 2 diabetes in pregnancy?

Metformin lowers blood glucose by reducing hepatic glucose output, increasing insulin sensitivity and enhancing peripheral glucose uptake. Metformin is widely used in women with Type 2 diabetes of child-bearing age, many of whom become pregnant. Studies to date in Type 2 diabetes in pregnancy, gestational diabetes and polycystic ovarian syndrome are reassuring. Metformin is not considered teratogenic. There is sufficient evidence that metformin is safe used throughout pregnancy, with no worsening of obstetric or perinatal outcomes. Women may benefit from the lesser weight gain. The long-term risks to the offspring remain inadequately researched, with no evidence of harm up to 2 years, and no suggestions of later complications in countries using metformin for many years. Metformin is recommended for use in pregnancies complicated by Type 2 diabetes, but women should be informed of the evidence regarding its associated risks and benefits to enable an informed choice over its use.

Metformin compared with glyburide for the management of gestational diabetes

OBJECTIVE

To assess blood glucose control and neonatal outcomes when women with gestational diabetes mellitus (GDM) were treated with metformin or glyburide.

METHODS

When an appropriate diet was insufficient to control their blood glucose levels, women with GDM were randomized to a glyburide or a metformin treatment group. If the maximum dose was reached, the assessed drug was replaced by insulin. The primary outcome measures analyzed were maternal glucose levels during pregnancy, birth weight, and neonatal glucose levels.

RESULTS

The only significant difference in outcome between the 2 treatment drugs was that maternal weight gain during pregnancy was less in the metformin (n=40) than in the glyburide group (n=32) (10.3 kg vs 7.6 kg; P=0.02). No differences were found in treatment failure, mean level of fasting or postprandial plasma glucose, rate of participants with glycated hemoglobin, birth weight, rate of large-for-gestational-age newborns, or newborns with hypoglycemia.

CONCLUSION

The treatment of GDM with metformin or glyburide was found to be equivalent for both women and newborns.

Brick by brick: metformin for gestational diabetes mellitus?

Evaluation of: Balani J, Hyer SL, Rodin DA, Shehata H. Pregnancy outcomes in women with gestational diabetes treated with metformin or insulin: a case-control study. Diabet. Med. 26(8), 798-802 (2009). This paper reviews a case-control study, reported by Balani et al., comparing maternal and neonatal outcomes of women treated for gestational diabetes mellitus with either metformin or insulin. A cohort of 100 women treated with metformin alone, without insulin rescue, was compared with a retrospective cohort of 100 women treated with insulin. Results favored metformin. This paper discusses issues related to the safety and efficiency of metformin treatment during pregnancy, the attitudes of pregnant women toward treatment options, public health policy and the worldwide gestational diabetes mellitus epidemic, as well as the financial burden of therapy, particularly for developing countries. It also looks at the pathophysiology of gestational diabetes mellitus and the need for clinical trial assessment of combination oral-hypoglycemic therapy.

Metformin treatment for gestational diabetes

The prevalence of gestational diabetes mellitus (GDM) is rising as the pregnant population becomes older and more obese. This is concerning because GDM is associated with increased perinatal morbidity such as macrosomia and shoulder dystocia, and the need for instrumental delivery. In addition, the offspring of GDM women have increased long-term risks of obesity and type 2 diabetes. There is no doubt that treating women with GDM improves pregnancy outcomes. Conventionally this has been by diet and insulin. Although effective, insulin increases appetite leading to weight gain. It increases the risk of hypoglycaemia and needs to be given by injection. There is also a substantial cost in terms of time for teaching and educating patients. Metformin offers a logical alternative to insulin in GDM, by reducing insulin resistance. Recent trial evidence indicates it is safe and effective. We describe our experience with metformin in GDM and review the evidence.