In humans diet soda consumption was associated with increased waist circumference. In diabetes-prone mice aspartame raises fasting glucose levels.
"Data from this and other prospective studies suggest that the promotion of diet sodas and artificial sweeteners as healthy alternatives may be ill-advised. They may be free of calories but not of consequences," said Helen P. Hazuda, Ph.D., professor and chief of the Division of Clinical Epidemiology in the School of Medicine.
To examine the relationship between diet soft drink consumption and long-term change in waist circumference, the Health Science Center team assessed data from 474 elderly Mexican Americans and European Americans.
Diet soft drink users, as a group, experienced 70 percent greater increases in waist circumference compared with non-users.
Frequent users, who said they consumed two or more diet sodas a day, experienced waist circumference increases that were 500 percent greater than those of non-users.
In the related project, Ganesh Halade, Ph.D., Gabriel Fernandes, Ph.D., the senior author and professor of rheumatology and clinical immunology, and Fowler studied the relationship between oral exposure to aspartame and fasting glucose and insulin levels in 40 diabetes-prone mice.
Aspartame is an artificial sweetener widely used in diet sodas and other products.
The mice in the aspartame group showed elevated fasting glucose levels but equal or diminished insulin levels, consistent with early declines in pancreatic beta-cell function.
"These results suggest that heavy aspartame exposure might potentially directly contribute to increased blood glucose levels, and thus contribute to the associations observed between diet soda consumption and the risk of diabetes in humans," noted Fernandes.
The study was presented June 25 at the American Diabetes Association's Scientific Sessions.