Mar. 26, 2009
Excess Fat Puts Patients with Type 2 Diabetes at Greater Risk
As bulging waistlines continue to increase in the United States, so does the surge of diabetes. According to the American Diabetes Association, more than 90 percent of all people newly diagnosed with type 2 diabetes are overweight.
But why does excess weight increase one's risk of developing type 2 diabetes? Free fatty acids, cells that circulate in the bloodstream, might be a clue, says Guillermo E. Umpierrez, MD, professor of medicine at Emory University School of Medicine.
"Free fatty acids are leading candidates in the development of insulin resistance and hypertension in obese patients," says Umpierrez.
In a study published in the February 2009 issue of the Journal of Endocrinology and Metabolism, Umpierrez and his team evaluated the effect of sustained elevations of free fatty acids on a host of bodily functions including blood pressure, endothelial function, cardiovascular inflammatory markers, and the renin-angiotensin system - a hormone system that regulates blood pressure and water (fluid) balance.
"Our study highlights the importance of free fatty acids in the development of high blood pressure and diabetes in obese African-American patients," says Umpierrez.
Twenty-four African-American patients with type 2 diabetes, an average body mass index of 37 and normal blood pressure were admitted to the General Clinical Research Center at Grady Memorial Hospital. The participants were randomly assigned to receive a 48-hour emulsion lipid infusion of Intralipid/heparin or saline/heparin.
To understand the potential risks of high levels of free fatty acids, researchers say it's important to know the mechanisms of diabetes and the condition that often precedes it, insulin resistance.Insulin is a hormone produced by the pancreas that allows blood sugar (glucose) to be used by cells in the body as energy or stored for later use. In insulin resistance, the cells of the body become resistant to insulin and less receptive to the blood sugar they need. Once insulin resistance develops, type 2 diabetes could result.
Researchers say diabetes treatment is not just about glucose anymore – obesity as well as dietary factors may contribute to the development of hypertension, insulin action and cardiovascular complications. In addition, high levels of free fatty acids, by diminishing the insulin action of disposing of glucose in peripheral tissues, may increase carbohydrate intolerance and lead to diabetes.
In this study, within just four hours of lipid infusion, Umpierrez and his team noted blood pressure had significantly increased in the participants, reaching a peak increment of 13 mm Hg in systolic and 5mm Hg in diastolic blood pressure at 24 hours. The effect on blood pressure elevation was sustained and was associated with increased cardiovascular markers of inflammation and endothelial dysfunction.
Umpierrez' research team is currently investigating the effects of different lipid emulsions in critically ill patients requiring parenteral (by injection) nutrition. He has obtained permission from the U.S. Food and Drug Administration to use olive oil as a potential nutrient in hospitalized patients. He believes olive oil, a monounsaturated fatty acid, is a better lipid formulation than Intralipid (brand name of a fat emulsion), causing less inflammation and endothelial dysfunction.
Reference: "Intravenous Intralipid-Induced Blood Pressure Elevation and Endothelial Dysfunction in Obese African-Americans with Type 2 Diabetes." Umpierrez, Guillermo E; Smiley, Dawn; Robalino, Gonzalo et al. The Journal of Clinical Endocrinology & Metabolism: Volume 94(2) pp 609-614.
The Robert W. Woodruff Health Sciences Center of Emory University is an academic health science and service center focused on missions of teaching, research, health care and public service.