Effect of "Nicotinamide Mononucleotide" (NMN) on Cardiometabolic Function

Inclusion Criteria: * Postmenopausal women 55-75 years old * BMI 25.0-44.9 kg/m² * Fasting plasma glucose concentration ≥100 mg/dl, OGTT 2 hour glucose ≥ 140 mg/dl, HbA1C ≥5.7%, or HOMA-IR ≥2.5 Exclusion Criteria: * Diabetes * Premenopausal or menopause \<1 year * Persons who have received hormone replacement therapy within the past 6 months * Persons who take vitamin B supplementation and are not willing to discontinue supplementation for 3 weeks before and during the entire study period. * Structured exercise: ≥75 min/wk of vigorous exercise (e.g., jogging, activity that causes heavy breathing and sweating) or ≥150 min/wk of low intensity physical activity (e.g., brisk walking). * Unstable weight (\>3% change during the last 2 months before entering the study) * Significant organ system dysfunction or disease * Present cancer or history of cancer that has been in remission for \<5 years * Polycystic ovary syndrome * Major psychiatric illness * Use of medications known to affect study outcome measures (e.g., steroid) or increase the risk of study procedures (e.g., anticoagulants) that cannot be temporarily discontinued for the study * Metal implants * Smokes cigarettes * Persons who consume \>14 units of alcohol per week * Unable or unwilling to follow the study protocol or who, for any reason, is considered an inappropriate candidate for the study by the research team.