University of Michigan, Michigan State, and Wayne State announce diabetes research news

Within 24 hours of each other, all three local major universities announced research news about diabetes. A University of Michigan study described how low-carbohydrate meals after exercise may benefit diabetics. At MSU, a researcher identified the cell mechanism leading to diabetic blindness. Finally, a WSU researcher received stimulus money to research the genetic components of heart disease and diabetes; she also received a second grant to study the effect of PCBs on breast cancer.

University of Michigan

New research showed that meals eaten after each exercise session have an important impact on controlling blood sugar. The researchers found that people who ate meals that were relatively low in carbohydrates but not low in calories improved control of their blood sugar levels well into the next day. In contrast, eating meals with fewer calories than one burned after exercise resulted in an improvement in blood sugar no different from eating enough calories to match the energy expended during exercise. Therefore, exercise can improve the control of blood sugar even without cutting calories.

In a press release, Jeffrey Horowitz, professor in the School of Kinesiology at University of Michigan and senior author of the study, stressed that weight loss is important for improving metabolic health in overweight people who are at risk for diabetes, but these study results suggest that people can still acquire some key health benefits from exercise without under-eating or losing weight. Horowitz also noted that their findings do not suggest that people at risk for diabetes should go on strict low-carbohydrate diets, as the research participants still ate more than 200 grams of carbohydrates in the hours after exercise as part of the so-called low carbohydrate treatment. In contrast, some of the popular low-carbohydrate diets can restrict carbohydrate intake to less than 20 grams per day.

"Carbohydrates are a very important part of a balanced diet, especially in people who exercise regularly," Horowitz said. "In general, it is important to replenish at least some of the carbohydrate stores used up during exercise so you have this major fuel source ready for your next exercise session."

In addition to Horowitz, Sean A. Newsom, Simon Schenk, Kristin M. Thomas, Matthew P. Harber, Nicolas Knuth, all of the School of Kinesiology, and Naila Goldenberg, Department of Internal Medicine, U-M Health System, contributed to the paper, "Energy deficit after exercise augments lipid mobilization but does not contribute to the exercise-induced increase in insulin sensitivity," which was published online in the Journal of Applied Physiology.

Michigan State University

Susanne Mohr, MSU associate professor of physiology, has discovered the process that causes retinal cells to die during diabetes, a condition known as diabetic retinopathy. This discovery could lead to new treatments that halt the damage to blood vessels in the eye caused by high blood sugar levels from diabetes. Diabetic retinopathy is a common side effect of diabetes and the leading cause of blindness in young adults in the United States. It’s estimated that between 40 percent and 45 percent of people diagnosed with diabetes have some degree of diabetic retinopathy.

Mohr found that diabetic retinopathy was the result of the interaction of two proteins, siah-1 and GAPDH. The siah-1 protein, which is produced when blood sugar levels are high, serves as a type of chauffeur for GAPDH, shuttling the other protein into the nuclei of Müller cells, special cells that have contact with the blood vessels in the eye. When GAPDH accumulates in the nuclei of the Müller cells, they die, leading to the damage to the blood vessels associated with diabetic retinopathy. Mohr's research also found that lowering levels of siah-1 proteins stopped GAPDH from moving into the nuclei of Müller cells, which stopped them from dying.

"This is very exciting," Mohr said in a press release. "We know that we can't regulate production of GAPDH because it's necessary for producing energy throughout the body. But since siah-1 is produced only when glucose levels are high, regulating it doesn't cause any problems. If we can figure out how to stop siah-1 production, it may lead to new treatments for diabetic retinopathy."

Mohr's paper, co-authored with E. Chepchumba Yego, doctoral student at Case Western Reserve University, was published in the Jan. 29 issue of the Journal of Biological Chemistry.

Wayne State University

Melissa Runge-Morris, M.D., professor and acting director of the Institute of Environmental Health Sciences at Wayne State University and a resident of Detroit, Michigan, received $357,461 from the National Institutes of Health (NIH) to investigate the function of a liver enzyme that plays a central role in lipid (fat, oil, and steroid) metabolism. Disturbances in lipid metabolism set the stage for the emergence of metabolic diseases such as heart disease, liver dysfunction, and insulin resistant type II diabetes.

Results of the study will shed new light on diseases that occur as a function of disordered lipid metabolism. "Not everyone who is obese, for example, develops type II diabetes," Runge-Morris said in a press release. "We suspect this could be due to critical inter-individual differences in lipid metabolism. A better understanding of the molecular events that regulate the major players in lipid metabolism like SULT2A1 (an enzyme known to metabolize hormones and detoxify drugs, chemicals in the environment, and carcinogens, but also suspected of metabolizing intermediates of cholesterol metabolism) will provide us with the tools to recognize and prevent the development of serious metabolic diseases in humans."

Runge-Morris also received $418,000 from NIH to investigate the effect of polychlorinated biphenyls (PCBs) accumulated in breast tissue, beginning in the very early stages of development. "We're trying to understand if normal levels of PCBs that one might be exposed to in the environment accelerate breast cancer progression," Runge-Morris said.

Combined, her two grants totaled more than $775,000.

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For regular updates on diabetes, please read stories by Kendra VanderLee, the Detroit Diabetes Examiner.