Interaction Between Inorganic Nitrate Supplementation and Metformin in Individuals With Prediabetes

Inclusion Criteria:

* Individuals who can communicate meaningfully with the investigator and can provide written consent.
* Confirmed prediabetic individuals (ages 18-60 years old) (2-hour glucose of 140-199 mg/dL following OGTT test or HbA1c between 5.7-6.4% tested on two occasions within 6 months).
* Taking metformin (stable dose for at least a week) or naïve to metformin
* Sedentary (\<1 day/week of structured exercise)
* Be able to perform exercise on a cycle ergometer without assistance
* Stable medication regimen for the last 6 months
* If female, have a normal menstrual cycle

Exclusion Criteria:

* Estimated Glomerular filtration rate (GFR) ≤ 45
* Body mass index ≥ 40 Kg/m2
* HbA1c \> 6.4%
* Smokers within the last 5 years
* Has experienced significant weight loss \~3 kg in the last three months or is taking any weight loss drugs
* Current medical condition that prohibits exercising at high intensities
* Currently on hormone replacement of any kind
* History of myocardial infarction, cerebrovascular event, acute or unstable disease other than pre-diabetes or obesity
* Currently taking any of the following medications (calcium channel blockers, statins, ACE or renin inhibitors, angiotensin receptor blockers, organic nitrates (e.g., nitroglycerine) or recent regular use of inorganic nitrates, alpha- or beta-blockers, diuretics, proton pump inhibitors, PDE-5 inhibitors (e.g.,: Cialis, Viagra), or xanthine oxidase inhibitors (e.g.,: Allopurinol))
* Oral antibiotic use within the previous four weeks, including over-the-counter antibacterial mouthwash or a mouthwash containing chlorhexidine and unwilling to discontinue use
* Oral cancer/severe oral disease
* Uncontrolled hypertension (\>140/90)
* Had hysterectomy or oophorectomy
* Fetuses, neonates, children, prisoners, cognitively impaired, non-English speaking participants