News & Research

By: Felicia Breedy

31-July-2008 – Joachim Ix, MD from the University of California San Diego, and the Veterans Affairs San Diego Healthcare System is conducting important research on diabetes and its effects on older persons. He is the recipient of an ADA-ASP Young Investigator Innovation Award in Geriatric Endocrinology. His study entitled “Fetuin-A and Incident Diabetes Mellitus in Older Persons” was published in JAMA on July 9, 2008 and featured in Diabetes Health.

Dr. Ix examined whether levels of fetuin-A indicated the development of type 2 diabetes in older people. Fetuin- A is a protein that is produced in and secreted by the liver and is circulated in the blood stream. Previous research suggests that fetuin-A binds to insulin receptors in muscle and fat, inhibiting insulin and causing insulin resistance. This inhibition of insulin could contribute to the development of type 2 diabetes.

In this longitudinal study of six years, Dr. Ix randomly selected participants, men and women, black and white, 70 to 79 years old. These individuals were recruited from the Health, Aging, and Body Composition (Health ABC) Study and were diabetes-free. The study enrolled a total of 513 participants, who were followed for six years for the development of diabetes.

Blood samples were obtained from the participants at their baseline study visit, and fetuin-A was measured using a human fetuin-A enzyme linked immunosorbent assay kit. Study participants self-reported physical activity levels, age, sex, and race. Researchers also measured the participants for regional adiposity, i.e. fat area, their waist circumference and seated blood pressure. Follow-up visits included telephone contact every six months, annual clinic visits, and fasting plasma glucose measurements. The results of this study included 135 cases of incident diabetes of which 71 cases were due to fasting plasma glucose of 126 mg/dl or greater, 22 cases were due to new use of anti-diabetic medication, and 42 cases were due to a self-reported diagnosis by a physician.

After data analysis, Dr. Ix concluded that higher serum fetuin-A levels are associated with incident diabetes mellitus in humans. This association was independent of physical activity, inflammatory biomarkers, and other recognized risk factors for diabetes. One-third of the association may have been mediated by visceral adiposity, i.e., abdominal fat. After adjusting for this adiposity, the association proved to be statistically insignificant. These study results provide insight into the relation between fetuin-A and incident diabetes in humans.

(Ix JH, Wassel CL, Kanaya AM, Vittinghoff E, Johnson KC, Koster A, Cauley JA, Harris TB, Cummings SR, Shlipak MG; Health ABC Study. Fetuin-A and incident diabetes mellitus in older persons. Journal of the American Medical Association. 300(2):182-8, 2008 Jul 9.)