Study: Link Between Diabetes And Dementia

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Diabetes, blood sugar test, generic (LaPook piece)

A study was released Tuesday that has important information for older diabetics, reports CBS News medical correspondent Dr. Jon LaPook. More than 23.5 million Americans have diabetes, and half of them are over 60. Researchers have discovered a link between that disease and dementia.

There's a new danger for diabetics: letting blood sugar get too low may damage the brain.

"In older patients with Type 2 diabetes, those with a history of hypoglycemic events were at greater risk of dementia when they were in old age," said Dr. Rachel Whitmer, the study's lead author.

The study, to be published Wednesday in the Journal of the American Medical Association, found the increased risk of dementia looked at over 16,000 elderly Type 2 diabetics. Those never hospitalized with low blood sugar had a 10 percent chance of dementia. That risk increased by 45 percent after one hospitalization, 115 percent after two, and 160 percent after three or more.

"When the sugar levels drop, there is impairment of brain function, particularly memory and attention. If it drops long enough and low enough, it can cause long term damage," said Dr. Gayatri Devi. "Unfortunately for us, the part of the brain that's most susceptible to low blood sugars is also the seat of memory, the hippocampus."

Blood sugar crashes either when patients eat too little or take too much medication, such as insulin. Fifty-eight year old California school superintendent Jim Negri knows what that feels like.

"Lightheaded. Some dizziness. Sometimes a clammy feeling," Negri described.

Even diabetics without hypoglycemia are more likely to have memory problems. So Negri is doing everything he can to keep his blood sugar properly balanced through diet, exercise and medication.

"Anything that's bad for the heart, which includes obesity, diabetes, hypertension - all of those will also be bad for the brain," Devi said.

The message from the study is that diabetics should really control their blood sugar, LaPook said. It shouldn't be too high - or too low.

  • Jonathan LaPook

    Dr. Jonathan LaPook is the chief medical correspondent for CBS News. Follow him on Twitter at @DrLaPook