University of Rochester Doctor Finds Kidneys’ Crucial Role in Controlling Diabetes

Findings may lead to reduction in number of potentially lethal comas Appearing in May Diabetes

May 05, 1999

Kidneys form a pivotal part of the system that maintains glucose levels in the body, says a University of Rochester researcher in the May issue of Diabetes. Diabetes, the disease that arises from the loss of this control, affects 16 million people a year (50,000 in the Rochester area), killing 179,000 of them. The findings show new ways doctors may be able to more accurately control diabetes, possibly even replacing insulin in some patients.

John E. Gerich, M.D., has found that the kidneys increase the release of glucose into the blood during hypoglycemia, which until now doctors have thought was done only by the liver. Glucose, or blood sugar, is the main source of energy for the body, but too much of it in the blood can be harmful. Insulin, normally secreted from the pancreas, lowers that level of glucose to safe limits, but in diabetics the pancreas is malfunctioning so sufferers must rely on drugs that help the pancreas release insulin, or on injections of insulin itself. If diabetics give themselves too high a dose of insulin or the drugs cause too much insulin secretion, blood sugar levels can drop dangerously low, sending the person into a hypoglycemic coma. People with diabetes have a one in ten chance of falling into a hypoglycemic coma every year of their lives. Fifteen percent of children with diabetes die because of such comas.

Gerich’s has found that the kidneys contribute just as much glucose as the liver – and more importantly, that different hormones control the liver and kidney secretions.

"It may be possible to tell the liver to slow down the production of glucose while leaving the kidneys alone," explains Gerich. "That way, we reduce the amount of glucose in the blood, but the kidney’s are still there as a back-up system in case glucose levels suddenly become too low."

Current treatments suppress both the liver and kidneys’ glucose secretion. With a treatment tailored to block either the liver or the kidney from producing glucose, doctors can control the approximate levels of glucose while letting the body fine-tune the levels, keeping them within healthy limits. This could help keep people with diabetes from experiencing hypoglycemia or other complications arising from extreme blood sugar levels.

To measure the amount of glucose released by the kidneys, Gerich injected volunteers with a small amount of radioactive glucose. As the volunteers’ blood sugar levels dropped, both the liver and kidneys reacted by secreting glucose and Gerch calculated how much of the radioactive glucose was secreted by the kidney.

The findings also may explain why people with kidney failure suffer from low blood sugar levels.

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