If you have diabetes, you may know that insulin levels can have a direct impact on your risk of complications such as kidney damage and heart disease. What you may not know is that insulin levels may affect the brain too.
"Even people who study diabetes may not always consider the impact of insulin in the brain," says Rita Kalyani, MD, assistant professor of medicine at Johns Hopkins University in Baltimore. "But insulin does play a role in the formation of synapses, storing memories, and other brain functions." Studies have linked insulin levels with appetite, energy balance, and body temperature too.
It appears that diabetes and insulin problems may be connected to a higher risk of serious conditions such as Alzheimer's disease and Parkinson's disease. Could diabetes-related insulin problems play a role in causing these conditions?
"I don't think we have the data yet, but it's possible that conditions like Alzheimer's disease are related to insulin problems," says C. Ronald Kahn, MD, professor of medicine at Harvard Medical School and vice chairman of the Joslin Diabetes Center Board. The potential connection concerns him. "Type 2 diabetes is already an epidemic and more and more people are developing it an earlier age," he tells WebMD. "We just don't know what effect it will have on their brains."
So, what can you do to stay healthy with diabetes? Here's what you need to know.
What Does Insulin Do?
Insulin is a natural hormone in the body. One of its key roles is helping cells absorb glucose or sugar in the blood for energy.
In people with type 1 diabetes, the pancreas does not make insulin. In people with type 2 diabetes, the pancreas makes insulin, but their bodies can't use it efficiently. In either case, the level of sugar in the blood rises, damaging cells throughout body.
Experts aren't sure how insulin works in the brain, but it seems to play many roles. Even in a healthy person, insulin changes that follow a high-carb meal change brain function, says Kahn.
Diabetes, Insulin, and the Brain
So how might diabetes and insulin problems affect the brain? "In people with diabetes, the brain doesn't seem to become insulin resistant in the same way that other organs in the body do," Kahn says. "But there do seem to be changes in insulin signaling in the brain."
People with diabetes seem to have a higher risk of Alzheimer's disease. They may have a higher risk of Parkinson's disease and Huntington's disease too. Insulin problems seem to be connected. Studies have found that insulin levels in certain regions of the brain associated with memory are much higher in healthy people than in people with Alzheimer's disease.
In people with Alzheimer's disease, a protein called beta-amyloid builds up, forming plaques on the brain. Abnormal insulin levels may make it harder for the body to break these plaques down.
The apparent connection between diabetes and Alzheimer's disease has led some researchers to make a controversial claim. Not only could diabetes increase the risk of Alzheimer's disease, they argue, but Alzheimer's disease is itself a form of diabetes that primarily affects the brain. Some have gone so far as to give Alzheimer's disease a new name: type 3 diabetes. But many diabetes experts are not convinced.