Scientists at the leading Swedish medical university Karolinska Institutet have now disclosed the mystery how alcohol may cause exaggerated insulin secretion resulting in severe hypoglycemia (too low blood sugar). This mechanism, which is described in the latest number of Endocrinology, explains how alcohol ingestion may harm the human brain by decreasing the blood glucose concentration to inappropriately low levels.

Hypoglycemia induced by alcohol ingestion is a well known clinical problem in diabetic patients. However, the mechanisms underlying this phenomenon have largely remained elusive. Since insulin secretion can be rapidly tuned by changes in pancreatic microcirculation, scientists at the Stockholm South Hospital Diabetes Research Center, Karolinska Institutet, evaluated the influence of alcohol administration on pancreatic islet blood flow and dynamic changes in insulin secretion and blood sugar levels.

"We have now found that alcohol exerts substantial influences on pancreatic microcirculation by evoking a massive redistribution of pancreatic blood flow from the exocrine into the endocrine (insulin-producing) part via mechanisms mediated by the messenger molecule nitric oxide and the vagus nerve, augmenting late phase insulin secretion, and thereby evoking hypoglycemia" says lead investigator Åke Sjöholm.

According to Professor Sjöholm the discovery is very important. This novel mechanism may in part underlie the well known hypoglycemic properties of alcohol in diabetic patients or in alcoholics with hepatic failure.

Investigators note that their study might also be relevant to "the derailed metabolic situation in diabetic subjects." Alcohol intake might provoke sustained hypoglycemia in type 2 diabetes patients being treated with hypoglycemic sulfonylureas, such as glibenclamide, because many of these drugs have a long biological half-life. Furthermore, many alcoholics are malnourished and/or have liver cirrhosis and might therefore be unable to mount a gluconeogenetic response to hypoglycemia, Professor Sjöholm says.