Ralph A. DeFronzo, M.D.

FDA issued a warning letter to Dr. Ralph A. DeFronzo, a clinical investigator at the University of Texas Health Science Center in San Antonio, following a December 2024 inspection of two clinical investigations involving investigational drugs, one of which involved GLP-1 receptor agonist-related eligibility criteria. The letter cites two primary violations: (1) failure to ensure subjects met protocol eligibility criteria before enrollment — all seven enrolled subjects had disqualifying blood pressure readings, eGFR values, or were on excluded medications (SGLT2 inhibitors and GLP-1 receptor agonists) — and (2) failure to promptly report a material change in study design (from a double-blind placebo-controlled trial to a pilot feasibility study) to the IRB before enrolling and treating all seven subjects. FDA found Dr. DeFronzo's corrective responses inadequate and required a written response within 15 business days detailing actions taken to prevent future violations, warning that failure to adequately respond may lead to regulatory action.