Harvard Study Evaluates How Mice With Diabetes React to Fructose

The study found that in diabetic mice, a common sweetener appears to travel straight to the liver, where it causes fat to accumulate.

Fructose, the form of sugar found in table sugar and high-fructose corn syrup, may behave differently in those with diabetes, according to a Harvard study.

In findings to be published in eLife, researchers working with diabetic mice found that once consumed, fructose reacted with a protein that is activated by diabetes, and ships the fructose straight to the liver where it manufactures fat.

The study, which was based on both short-term and long-term feeding experiments, may shed light on what happens when people with diabetes consumer food and drink in which high-fructose corn syrup is used as a sweetener. Fructose is also found to be half of table sugar.

Fructose has been suspected for some time to be a bigger culprit than other forms of sugar in the rise of diabetes. Kimber Stanhope, PhD, RD, of the University of California at Davis has examined the adverse cardiometabolic effects on young adults after consuming fructose for very short periods of time. But finding this association is one thing, and declaring cause and effect is something else. Implicating high-fructose corn syrup has major implications because the low-cost sweetener is widely used in soda and processed foods.

The researchers conducted experiments with mice with and without the metabolic control protein called Txnip. The protein seems to act as a carrier, increasing the number of transporters that filter fructose across the gut wall to the liver, where it causes the build-up of fat and may trigger insulin resistance and hypertension. Insulin resistance leads to the development of type 2 diabetes.

Diabetes in the mice caused an increase in the protein, and, in turn, more fructose absorption. Those mice without the protein had less severe metabolic disease, even if they consumed sugar consistently for 6 months.

The researchers said more work needs to be done to understand the relationship between fructose and glucose, and how the mechanisms examined in this study relate to the transition from prediabetes to diabetes.

“The next big questions to answer are whether all forms of diabetes increase fructose absorption, and also whether the effects and mechanisms are similar in humans,” said Richard Lee, MD, of Harvard, who supervised the study.

Reference

Dotimas JR, Lee AW, Schmider AB. Diabetes regulates fructose absorption through thioredoxin-interacting protein [published online October 11, 2016]. eLife. 2016;5:e18313.