Metformin is prescribed to 50 million Americans annually, and is currently in widespread perinatal (pre-pregnancy, during pregnancy, and post-natal) clinical use. Over the past decade, clinical indications and pragmatic use of metformin have steadily expanded beyond the treatment of overt diabetes outside of pregnancy, and now include prediabetes and obesity, polycystic ovary syndrome, type 2 diabetes, and gestational diabetes. With its expanded use, questions of unintended long-term harm have arisen. The rationale underlying these concerns for metformin exposure during development as a consequence of expanded maternal use arises from its basic pharmacodynamics and mechanisms of action, which we and others hypothesize converge to disrupt important metabolic pathways during fetal life, which are necessary to establish normal birth weight and appropriate early post-natal growth trajectory. When combined with a maternal Western-style diet (WSD), fetal metformin exposure leads to accelerated early development of a pre-diabetic, pre-obese phenotype with evidence of obesity and insulin resistance in early adolescence (puberty onset). We are inspired by our preliminary data to pursue development of a non-human primate model of maternal metformin use. Powered as a three-armed mechanistic-based clinical study, we will determine the impact of metformin or placebo exposure from pre-pregnancy through lactation on the development of obesity and insulin resistance. This study is adequately powered to test the hypothesis that maternal metformin use in isolation or in conjunction with a maternal high fat diet renders low birthweight and aberrant catch-up growth, driving obesity and insulin resistance in the offspring by onset of puberty (approximately 3-4 years of age). In Aim 1, we will determine if early life metformin exposure in control and/or WSD-fed dams leads to low birthweight and aberrant catch-up growth, resulting in obesity and insulin resistance in pubertal juvenile offspring. In Aim 2, we will determine what the impact of metformin exposure in WSD-fed dams is on maternal, fetal (G145) and juvenile (to puberty onset) metabolic physiology. This will include core measures of maternal and fetal organ metabolism (liver, muscle, gut and pancreas). In Aim 3, we will determine whether weaning offspring onto a control diet can ameliorate or mitigate the effects of maternal metformin exposure in WSD-fed dams. Finally, in Aim 4 we will determine how early metformin exposure wields its molecular impact on control and WSD-induced alterations of core measures of maternal and fetal metabolism in the liver, gut, muscle, and pancreas. Considering the recently emerged epidemiologic evidence and known mechanisms of actions of metformin, there is a rational concern that rather than preventing developmental programming, metformin use during pregnancy may have unintended consequences of accelerating obesity and the metabolic syndrome epidemic in the next generation. The animal, specimen, and uniformly generated multi’omic data generated in the current proposal will collectively inform ongoing clinical trials and future clinical implementation.

Over the past decade, indications for the use of metformin have steadily expanded to now include not only overt diabetes outside of pregnancy, but prediabetes, obesity, polycystic ovary syndrome, gestational diabetes (GDM), and type 2 diabetes during pregnancy. With its expanded use, however, questions of unintended long-term harm to offspring exposed to metformin during gestation have arisen. The current proposal will generate a Rhesus macaque model and robust data necessary and sufficient to understand if, what, whether and how early life exposure to metformin (with and without maternal & post-weaning Western style diet feeding) renders offspring persistently susceptible to obesity and insulin resistance.