News & Research

By: Felicia Breedy

Allison Goldfine

American Diabetes Association-funded researcher Allison Goldfine, MD (Career Development Award), has uncovered a surprising discovery about the production of insulin. Proven in animal models, insulin is important in regulating its own production. Now, members of Dr. Goldfine's research laboratory in Boston, Massachusetts have confirmed in humans that when blood sugar levels rise in healthy people, insulin signals beta cells to increase production. Dr. Goldfine's paper was published in the online edition of the Proceedings of the National Academy of Sciences, February 22, 2010.

Dr. Rohit Kulkarni, MD, PhD (Basic Science and Mentor-Based Postdoctoral Fellowship Award), led the pilot experiments in mice a decade ago.  Several different studies in mice and isolated beta cells formed the basis for experiments in people. Eventually, beta cell insulin resistance and insulin secretion were linked whereas before they were believed to be separate processes.

Rohit Kulkarni

Dr. Goldfine wondered whether the same held true for humans as it did for mice. Dr. Goldfine states, "In people, insulin has long been thought to suppress the function of the beta cell, not stimulate it." Researchers in Dr. Goldfine's lab enlisted the help of healthy volunteers and under very careful conditions, they measured insulin production, administered human analog of insulin with glucose and coordinated doses to maintain normal glucose levels. Increasing the amount of glucose, researchers then monitored the additional production of insulin and found that insulin production did increase to higher levels when insulin was already present.

In a follow-up study, Dr. Goldfine and her team will examine whether the insulin signaling mechanism is damaged in people who exhibit early signs of insulin resistance which could eventually lead to type 2 diabetes. The investigation will not only help provide a greater understanding of how insulin production eventually declines with type 2 diabetes, but it will also lead to the possibility of new types of drugs for its treatment.
 
(Bouche C, Lopez X, Fleischman A, Cypess AM, O'Shea S, Stefanovski D, Bergman RN, Rogatsky E, Stein DT, Kahn CR, Kulkarni RN, Goldfine AB. Insulin enhances glucose-stimulated insulin secretion in healthy humans. Proc Natl Acad Sci U S A. 2010 Mar 9;107(10):4770-5. Epub 2010 Feb 22.)