This proposed study; Investigation of mechanisms for transmission of impaired glucose metabolism in infants exposed to diabetes in utero, will test the overarching hypothesis that impaired maternal substrate oxidation (metabolic inflexibility) and placental lipotoxicity are characteristics of diabetic pregnancies and in utero development within these conditions programs a metabolically inflexible phenotype in the offspring.

This translational research study will obtain paired measures of metabolic flexibility (postprandial RQ minus basal RQ) in response to a standardized meal by indirect calorimetry in mother:infant dyads of diabetic and non-diabetic pregnancies. The downstream effects of the intrauterine exposure to diabetes and gestational lipotoxicity will be tested in the infant: 1) at birth by studying adipogenic pathways and mitochondrial function in umbilical cord mesenchymal stem cells cultured in myogenic conditions[13], and 2) by studying metabolic flexibility in the infant in a whole body infant calorimeter in response to a standardized meal.

Mothers will be enrolled between (33-35 weeks of gestation) and their infants will be enrolled between 10-30 days of life with the following aims.

Aim 1. Characterize metabolic flexibility and lipotoxicity in diabetic and non-diabetic pregnancies.

Hypothesis 1A: In response to a standardized meal in late pregnancy, diabetic pregnancies will be metabolically inflexible (blunted switch in RQ from the fasted state to the postprandial state) compared to non-diabetic pregnancies matched for maternal age and pregravid BMI.

Hypothesis 1B: Placenta from diabetic pregnancies will have higher lipid content, reduced mitochondrial content and lower rates of mitochondrial oxygen consumption compared to placenta from non-diabetic pregnancies.

Aim 2. Test whether intrauterine exposure to maternal diabetes infers disordered substrate oxidation in offspring at birth (in myocytes cultured from umbilical cord mesenchymal stem cells) and early in postnatal life (metabolic flexibility in response to a standardized meal).

Hypothesis 2A: Umbilical cord mesenchymal stem cells cultured in myogenic conditions from diabetic pregnancies will have greater lipid content, reduced mitochondrial content, and lower rates of mitochondrial electron transport oxygen consumption and fatty acid oxidation.

Hypothesis 2B: In response to a standardized meal, offspring of diabetic pregnancies will be metabolically inflexible (blunted switch in RQ from the pre- to postprandial state) compared to offspring of non-diabetic pregnancies.

Inclusion Criteria (Mother):

• BMI between 20 kg/m2 and 40 kg/m2 prior to the current pregnancy (determined by self-report and confirmation of pregravid BMI of the index pregnancy from the prenatal record)
• Completion of standardized glucose tolerance testing (between 24-28 weeks gestation) in the index pregnancy; either a single 2 hour, 75g glucose tolerance test or the two-step: 1 hour 50g and 3 hour 100g glucose tolerance test to confirm diagnosis of gestational diabetes mellitus or normal glucose tolerance
• Medically cleared for participation in the study by primary care obstetrician or midwife
• Medically cleared for participation by the Medical Investigator
• Medical record release (prenatal record, hospital delivery record) for study staff to access information in the medical record related to the current and if applicable, the prior pregnancy.
• Willingness to enroll the infant in the study provided inclusion/exclusion criteria pertaining to the infant are met

Inclusion criteria (Infant):

• Born full-term (>37,0 weeks gestation)
• Available for clinical assessments between 10-30 days old
• Healthy

Exclusion Criteria (Mother):

• Use of insulin therapy in the index pregnancy
• History of preterm birth
• History of intrauterine growth-restriction
• Evidence of gestational hypertension (SBP >160 mmHg & DBP >110 mmHg)
• HIV or AIDS (self-reported)
• Planned termination of pregnancy or adoption or unwillingness to enroll the infant in the study

Exclusion Criteria (Infant):

• Using medications to treat a chronic condition (does not include use of vitamin supplements or PRN medication for flatulence)
• Unwilling or unable to be fed 2 fl oz of infant formula
• Diagnosed with a congenital abnormality or disability that would render testing unsafe or would interfere with data collection

Up to 20 pregnant women with and without gestational diabetes mellitus with a BMI between 20 kg/m2 and 40 kg/m2 prior to the current pregnancy.