Occasional Binge Drinking May Increase Risk for Type 2 Diabetes

A study conducted by an Association-funded researcher indicates that binge drinking may increase the risk for developing metabolic syndrome and type 2 diabetes. Many alcoholic beverages are high in “empty” calories, which can contribute to weight gain and insulin resistance. Yet in the January 30, 2013 issue of Science Translational Medicine, lead investigator Christoph Buettner, MD, PhD, found that consuming alcohol in a binge pattern induces insulin resistance independent of caloric intake. Rather, binge drinking appears to impair the way the brain responds to insulin, even well after the alcohol has been cleared from the system.

Consuming five alcoholic beverages within a two-hour time span for men (or four beverages within two hours for women) is considered binge drinking. According to a current report from the Centers for Disease Control and Prevention (CDC), more than 38 million Americans, or one in six people, engage in the habit, and the rate is climbing in populations at risk for diabetes, such as adults aged 65 and older.

Since prior studies had suggested that binge drinking as infrequently as once a month may be associated with diabetes, the Mount Sinai School of Medicine scientists began looking for changes in metabolism related to binge alcohol consumption. The laboratory team administered ethanol to rats for three consecutive days to simulate human binge drinking. More than two days after the last alcohol exposure – long after ethanol levels in the blood had become undetectable – the rats exhibited significantly higher plasma insulin levels and worsened glucose metabolism compared to those that were given nonalcoholic beverages with the same amount of sugar and calories.

A high level of plasma insulin is a hallmark of type 2 diabetes and indicates insulin resistance – that the body is unable to efficiently use insulin to metabolize glucose. The researchers noticed that after binge alcohol exposure, insulin resistance was most pronounced in the rats’ liver and fat tissue. The hypothalamus region of the brain normally contributes to the regulation of metabolism in the liver and fat, leading the investigators to examine insulin function in this area.

They found that indeed binge drinking disrupted the effects of insulin in the brain through increased expression of PTP1B, a gene that triggers inflammation and interferes with insulin signaling in the hypothalamus. When the scientists blocked the gene in the brain with a drug, insulin resistance was almost completely prevented in the alcohol-treated rats. Interestingly, natural aging and overeating, other common causes of insulin resistance also increase the expression of PTP1B in the brain.

“Insulin resistance has emerged as a key metabolic defect leading to type 2 diabetes and coronary artery disease (CAD),” said Dr. Buettner. “Someone who regularly binge drinks even once a week, over many years, may remain in an insulin-resistant state for an extended period of time, potentially years.”

Dr. Buettner’s research team is currently investigating exactly how binge drinking increases the expression of PTP1B. “If these results apply to humans, binge drinking is not only an epidemiological risk factor but also a direct cause of insulin resistance that sets the stage for the metabolic syndrome and type 2 diabetes.”

(C. Lindtner, T. Scherer, E. Zielinski, N. Filatova, M. Fasshauer, N. K. Tonks, M. Puchowicz, C. Buettner, Binge drinking induces whole-body insulin resistance by impairing hypothalamic insulin action. Sci. Transl. Med. 5, 170ra14 (2013).)