ObjectiveThe effect of metformin on weight reduction in polycystic ovary syndrome (PCOS) is often unsatisfactory. In this study, we investigated the potential add-on effect of treatment with the glucagon-like peptide-1 receptor agonist liraglutide on weight loss in obese nondiabetic women with PCOS who had lost <5% body weight during pretreatment with metformin.MethodsA total of 40 obese women with PCOS, who had been pretreated with metformin for at least 6 months, participated in a 12-week open-label, prospective study. They were randomized to one of three treatment arms: metformin (MET) arm 1000 mg BID, liraglutide (LIRA) arm 1.2 mg QD s.c., or combined MET 1000 mg BID and LIRA (COMBI) 1.2 mg QD s.c. Lifestyle intervention was not actively promoted. The primary outcome was change in body weight.ResultsThirty six patients (aged 31.3±7.1 years, BMI 37.1±4.6 kg/m2) completed the study: 14 on MET, 11 on LIRA, and 11 on combined treatment. COMBI therapy was superior to LIRA and MET monotherapy in reducing weight, BMI, and waist circumference. Subjects treated with COMBI lost on average 6.5±2.8 kg compared with a 3.8±3.7 kg loss in the LIRA group and a 1.2±1.4 kg loss in the MET group (P<0.001). The extent of weight loss was stratified: a total of 38% of subjects were high responders who lost ≥5% body weight, 22% of them in the COMBI arm compared with 16 and 0% in the LIRA and MET arm respectively. BMI decreased by 2.4±1.0 in the COMBI arm compared with 1.3±1.3 in LIRA and 0.5±0.5 in the MET arm (P<0.001). Waist circumference also decreased by 5.5±3.8 cm in the COMBI arm compared with 3.2±2.9 cm in LIRA and 1.6±2.9 cm in the MET arm (P=0.029). Subjects treated with liraglutide experienced more nausea than those treated with metformin, but severity of nausea decreased over time and did not correlate with weight loss.ConclusionsShort-term combined treatment with liraglutide and metformin was associated with significant weight loss and decrease in waist circumference in obese women with PCOS who had previously been poor responders regarding weight reduction on metformin monotherapy.
BackgroundLiraglutide 3 mg was recently approved as an anti-obesity drug. Metformin is weight neutral, yet it could enhance the therapeutic index of GLP-1 agonist. We compared weight-lowering potential of liraglutide 1.2 mg in combination with metformin to liraglutide 3 mg monotherapy in obese PCOS.MethodsThirty obese women with PCOS (aged 33.1 ± 6.1 years, BMI 38.3 ± 5.4 kg/m2) were randomized to combination (COMBO) of metformin (MET) 1000 mg BID and liraglutide 1.2 mg QD (N = 15) or liraglutide 3 mg (LIRA3) QD alone (N = 15) for 12 weeks. The primary outcome was change in anthropometric measures of obesity.ResultsBoth treatments led to significant weight loss (−3.6 ± 2.5 kg, p = 0.002 in COMBO vs −6.3 ± 3.7 kg, p = 0.001 in LIRA3). BMI and waist circumference reduction in LIRA3 was greater than in COMBO (−2.2 ± 1.3 vs −1.3 ± 0.9 kg/m2
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p = 0.05 and −4.2 ± 3.4 vs −2.2 ± 6.2 cm, p = 0.014, respectively). Both interventions resulted in a significant decrease of post-OGTT glucose levels. COMBO significantly reduced total testosterone and was associated with less nausea.ConclusionsShort-term interventions with COMBO and LIRA3 both led to significant improvement of measures of obesity in obese PCOS, LIRA3 being superior to COMBO. However, COMBO further improved androgen profile beyond weight reduction and was associated with better tolerability.Trial registrationThe study was retrospectively registered with ClinicalTrials.gov (NCT02909933) on 16th of September 2016.
Metformin is the most commonly used treatment to increase insulin sensitivity in insulin-resistant (IR) conditions such as diabetes, prediabetes, polycystic ovary syndrome, and obesity. There is a well-documented correlation between glucose transporter 4 (GLUT4) expression and the level of IR. Therefore, the observed increase in peripheral glucose utilization after metformin treatment most likely comes from the induction of GLUT4 expression and its increased translocation to the plasma membrane. However, the mechanisms behind this effect and the critical metformin targets are still largely undefined. The present review explores the evidence for the crucial role of changes in the expression and activation of insulin signaling pathway mediators, AMPK, several GLUT4 translocation mediators, and the effect of posttranscriptional modifications based on previously published preclinical and clinical models of metformin’s mode of action in animal and human studies. Our aim is to provide a comprehensive review of the studies in this field in order to shed some light on the complex interactions between metformin action, GLUT4 expression, GLUT4 translocation, and the observed increase in peripheral insulin sensitivity.
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