Robert A. Rizza, M.D.

Robert A. Rizza, M.D., studies the regulation of carbohydrate metabolism in humans. The long-term goal of Dr. Rizza's research team is to develop rational and effective therapies for the treatment and prevention of diabetes mellitus and its associated complications.

Dr. Rizza's team makes extensive use of isotopic dilution (stable and radioactive) techniques, indirect calorimetry, organ catheterization (hepatic, leg and forearm) and mathematical models.

They also use glucose and insulin clamps, as well as computer-generated insulin and glucose infusion algorithms, to assess the impact of physiologic changes in glucose, insulin, glucagon, cortisol, incretins and various substrates (such as free fatty acids) on carbohydrate, fat and protein metabolism in people with and without diabetes.

Dr. Rizza's research has been funded by the National Institutes of Health and American Diabetes Association, among other organizations.

Focus areas

• What causes fasting and postprandial hypoglycemia? Dr. Rizza is working to better understand how glucose balance abnormalities alone and in combination cause hyperglycemia in people with diabetes mellitus.

  At any given time, the rate of change in plasma glucose concentration is determined by the balance between the amount of glucose entering the blood stream and the amount of glucose leaving the blood stream. The former is derived from food or the liver, while the latter is determined by the rate of uptake of glucose by insulin-dependent and insulin-independent tissues.

  This balance is disrupted in people with diabetes due to alterations in insulin secretion, insulin action and glucose effectiveness (the ability of glucose to stimulate its own uptake and to suppress its own release).

• Why are blood sugars high in people with diabetes? Dr. Rizza is interested in the effects of obesity, diabetes and various treatment modalities on the regulation of hepatic glycogenolysis, gluconeogenesis and glycogen synthesis in humans.
• How do we best treat diabetes? Dr. Rizza's team is examining the impact of different routes of insulin (portal versus peripheral) and glucose (enteral versus intravenous) delivery on glucose tolerance.

Significance to patient care

Professional highlights

• Banting Medal for Scientific Achievement, American Diabetes Association, 2010
• Executive Dean for Research, Mayo Clinic, 2007-present
• President, American Diabetes Association, 2005-2006
• Associate Editor — Diabetic Medicine (2000-2006), American Journal of Physiology (1995-2000), Diabetes (1989-1991), Diabetes Care (1982-1987)