Saxagliptin + Metformin Compared to Saxagliptin or Metformin Monotherapy in PCOS Women With Impaired Glucose Homeostasis

A major change in the treatment of polycystic ovary syndrome (PCOS) was initiated by the understanding that many women with this disorder compensate insulin resistance with a period of hypersecretion of insulin by the pancreatic ß-cell. In addition, women with PCOS have significantly higher basal insulin secretory rates, reduced insulin clearance rates, and attenuated secretory responses to meals. The decreased postprandial response in these patients resembles the ß-cell dysfunction of type 2 diabetes (DM2) and may account for the increased incidence of impaired glucose tolerance in this population. Current research has shown that the use of diabetes management practices aimed at reducing insulin resistance and hyperinsulinemia (such as weight reduction and the administration of oral antidiabetic drugs) in women with PCOS can not only improve glucose and lipid metabolism but can also reverse testosterone abnormalities and restore menstrual cycles.

The optimal modality for long-term treatment of PCOS should positively influence androgen synthesis, sex hormone binding globulin (SHBG) production, the lipid profile, insulin sensitivity, and clinical symptoms including hirsutism and irregular menstrual cycles. Improvement of insulin sensitivity may reverse some of the demand on the ß-cell and promote improvement in glucose tolerance. However, while insulin resistance plays a key role in the predisposition to diabetes in PCOS; defects in insulin secretion also appear to contribute to its development. Preferably therapy for women with PCOS should also produce no weight gain, hypoglycemia, or other limiting or unmanageable side effects as well as preserve or enhance ß-cell function.

Presently, in the literature, there are described new, more efficient methods of diabetes prevention in groups with a high risk of this disorder, which involve both, lifestyle modification and pharmacological therapies. Lifestyle intervention was found to reduce the incidence of type 2 diabetes by 58% and metformin by 31% as compared with placebo. The use of rosiglitazone in subjects with prediabetes resulted in a 60% reduction of the diabetes incidence rate. Whether pharmacological therapy should be prescribed for diabetes prevention is an open question given that waiting to add drug therapy until diabetes develops can arrest β-cell decline, albeit at a lower level of β-cell function than when medications are used for prevention. Studies are needed for optimal postpartum and long-term health of women who have had gestational diabetes (GDM). Considerable recent evidence suggests that incretin-based therapies may be useful for the prevention of DM2. Whereas native GLP-1 has a very short half-life, continuous infusion of GLP-1 improves first and second-phase insulin secretion suggesting that early GLP-1 therapy may preserve ß-cell function in subjects with IGT or mild DM2. Incretin mimetics and inhibitors of the protease dipeptidyl peptidase (DPP)-4 use the anti-diabetic properties of the incretin hormone, glucagon-like peptide (GLP)-1 hormone to augment glucose-induced insulin secretion in a highly glucose-dependent manner, thus preventing GLP-1 alone from provoking hypoglycemia. Additional beneficial effects of GLP-1 on endocrine pancreatic islets are that it 1) supports the synthesis of proinsulin to replenish insulin stores in β-cells; 2) reduces the rate of β-cell apoptosis when islets are incubated in a toxic environment (glucotoxicity, lipotoxicity, cytotoxic cytokines); and 3) promotes differentiation of precursor cells with the ability to develop into β-cells and proliferation of β-cell lines, and in whole animals (rodent studies), this leads to an increased β-cell mass within a few days or weeks. Furthermore, GLP-1 can lower glucagon concentrations, i.e., induce α-cells to respond again to the inhibitory action of hyperglycemia, while leaving the counterregulatory glucagon responses undisturbed, as in the case of hypoglycemia. Additional activities of GLP-1 are the deceleration of gastric emptying, which slows the entry of nutrients into the circulation after meals, a reduction in appetite, and earlier induction of satiety, leading to weight reduction with chronic exposure. Inhibition of DPP-4 increases the concentration of GLP-1 and may potentially delay disease progression in prediabetes considering the β-cell function improvement in DM2 and β-cell mass shown to increase in animal models. The objective of the present proposal is to compare the clinical, endocrine and metabolic effects of therapy with combination saxagliptin and metformin to saxagliptin and metformin monotherapy in women with PCOS and prediabetic hyperglycemia (IFG, IGT or IFG/IGT). Since aberrant first-phase insulin secretion and impaired suppression of endogenous glucose production are major contributors to postprandial hyperglycemia and development of DM2, the effects of saxagliptin to target these defects, and normalize glucose excursions are likely to be clinically significant in patients with PCOS and impaired glucose regulation. This study will evaluate the impact of treatment with combination of metformin and saxagliptin (Kombiglyze XR) compared to saxagliptin (Onglyza) or metformin XR (Glucophage XR) monotherapy over a 16-week period on glycemia and insulin action (fasting, 2 hour, and mean stimulated glucose levels, insulin sensitivity and secretion), hyperandrogenism (total T, DHEAS, SHBG and calculated free androgen index [FAI]), cardiometabolic markers (lipid profile, blood pressure), and anthropometric measurements (BMI, waist: hip ratio, absolute weight) in patients with PCOS and prediabetic hyperglycemia