Insulin can protect diabetic brains.

Staying on top of diabetes treatments may prevent some of the brain atrophy and cognitive deficits that typically accompany this disease, say researchers studying mice.

Previous research in people had shown that diabetes, whether diagnosed in youth or adulthood, can lead to learning and memory problems. Recently, some scientists demonstrated that the brains of diabetic patients gradually shrink and develop abnormalities in white matter, factors that may be responsible for cognitive deficits.

It's unknown whether these problems are inevitable consequences of diabetes or whether consistently treating the disease with insulin can prevent them, says Cory Toth of the University of Calgary in Canada. He and his colleagues looked into this question by testing mice with a form of diabetes.

Several weeks after the animals' disease was well established, the researchers started training those mice and non-diabetic ones to complete a variety of cognitive tasks--for example, to locate a platform in a pool of water or to find a treat hidden in a maze. Two weeks after these training sessions began, the researchers started giving some of the diabetic animals daily doses of insulin. Other diabetic mice received saline instead.

Several months after the training ceased, the saline-treated diabetic mice could no longer complete the cognitive tasks. But the insulin-treated animals and the healthy mice continued to perform well. When the scientists examined the diabetic animals' brains, they found that insulin appeared to have slowed the brain atrophy associated with the disease.

If future studies find that these results are relevant to people, Toth says, this information could give diabetic patients an additional reason to keep their disease under control.--C.B.