Targeting the liver with insulin could be the best way to treat type 1 diabetes, US researchers have claimed.
A team from the Vanderbilt University Medical Center set out to investigate whether people with type 1 diabetes experience resistance to the manufactured insulin they take and consider how insulin delivery may affect the risk of complications.
To date, it is widely believed that high levels of glucose leads to greater risk of diabetes-related complications, but lead researcher Dr Justin Gregory, who was diagnosed with type 1 diabetes more than 19 years ago, does not agree.
The assistant professor of Pediatrics at the medical centre said: “There’s more to treating type 1 diabetes than just bringing down high blood sugar.”
He thought the answer might have more to do with the way insulin is delivered into muscle. In people who do not have diabetes, insulin is produced by the pancreas first before it travels via the liver, halving the amount of the hormone before it is despatched to the muscle.
However, when insulin is injected under the skin in those with diabetes, a key part of that process is bypassed, and the liver is initially missed.
Dr Gregory said that injecting insulin under the skin meant he had “too much insulin at muscle and not enough at liver—all because I’m putting insulin in the wrong place”.
“Restoring that balance is important toward helping people with type 1 diabetes reduce their risk of heart disease,” he added.
Dr Gregory’s theory with regard to heart disease risk is based on association between insulin resistance and inflammation.
To prove the theory that people with type 1 diabetes have resistance to the insulin they take, the team carried out tests on people with type 1 diabetes and compared the results with people with a different form of diabetes, known as GCK-MODY.
People with GCK-MODY have a genetic condition, affecting the GCK (glucokinase) gene, that affects the pancreas’ sensing of how high blood glucose levels are. This leads to people with GCK-MODY having higher than normal blood glucose levels.
By choosing people with GCK-MODY as a comparison group, the team were able to compare differences in tests with two groups that both had similarly high blood glucose levels.
Both groups had their blood glucose adjusted to the same level, then their insulin levels were compared. The MODY group’s insulin levels were deemed in the healthy range, whereas insulin levels among those with type 1 were 2.5 times higher.
Dr Gregory said his study “brings to light the need to develop therapeutic strategies to keep the appropriate balance of insulin between the liver and peripheral insulin-sensitive tissues”.
He added: “We need to come up with ways of delivering insulin that replicate that normal balance of insulin.”
The findings have been published in the journal Diabetes.