Diabetes happens when the body either doesn't make enough, or doesn't properly use, the hormone insulin.
Managing blood sugar is key to keeping diabetes under control.
For years, patients have been encouraged to keep levels low, but researchers at Kaiser Permanente found low blood sugar in patients with Type 2 diabetes, the most common kind, can lead to Alzheimer's and other forms of dementia.
"Having a balance of blood sugar is a very key issue," explains Dr. Rachel Whitmer. "It's not just about not getting too high. It's also about not getting too low."
Kaiser looked at thousands of patients for more than two decades and found those hospitalized just once for severe hypoglycemia, low blood sugar, were 26 percent more likely to develop dementia.
Three hospital visits nearly doubled the risk.
Researchers are also finding ways to help people with Type 1 diabetes, those who must take extra insulin.
Northwestern University found adult stem cell transplants lowered, and in some cases eliminated, the need for those shots for up to four years.
"Just to be able to take someone and have them insulin-free with normal blood sugars on no medications for many years in the first attempt, you know, is a step forward," noted Northwestern's Dr. Richard Burt.
Similar research transplanting islets, hormone-producing cells from the pancreas, also allowed patients to be insulin-free, but it's very expensive.