Study of Beetroot Juice Nitrate Supplementation and Metformin Effects on Exercise, Blood Vessel Health, and Insulin Response in Adults with Prediabetes

What this Trial Is About

Researchers are studying whether short-term supplementation with inorganic nitrate, given as beetroot juice, can improve blood vessel health, insulin sensitivity, and exercise capacity in people with prediabetes. The study compares individuals currently taking metformin with those who have never taken it. The goal is to find non-drug options to help manage prediabetes and potentially prevent type 2 diabetes. Participants will receive either nitrate-rich beetroot juice or nitrate-depleted beetroot juice for 4 days. The nitrate-rich juice contains 6.45 mmol of nitrate twice daily for 3 days and a double dose 2 hours before a lab visit. After a minimum 7-day washout period, participants will switch to the other supplement in a randomized, double-blind crossover design. Two groups will be compared those on metformin and those who are metformin-naive. During the study, participants will undergo tests of vascular function, including pulse wave analysis and flow-mediated dilation, skin microvascular assessments, and exercise tests measuring peak oxygen uptake and time to exhaustion. An oral glucose tolerance test will assess insulin sensitivity. Researchers will also analyze blood and oral microbiome samples and monitor exercise responses and tissue oxygenation. The study lasts at least 4 days per supplement period with assessments following each phase.

Interaction Between Inorganic Nitrate Supplementation and Metformin in Individuals With Prediabetes