Extra Dose of Insulin After Eating May Improve Heart Health


A second smaller dose of insulin after eating is a simple way people with type 1 diabetes can cut cardiovascular risk, according to a small study in the UK. The catch, however, is that people with type 1 diabetes have to rethink how they use insulin and how it interacts with food.

“Looking at the science makes you realize this makes complete sense,” says Dr. Matthew Campbell, Senior Lecturer in Sport and Exercise Nutrition at Leeds Beckett University, who co-authored the results of the study. “Living with type 1 diabetes is difficult. But, this study shows a simple, pragmatic step that can be taken that we think will improve health.”

The study published in Diabetes and Vascular Disease Research on June 5, shows that taking a dose of insulin three hours after eating a meal high in fat helped reduce fat and inflammatory markers in the blood that lead to cardiovascular problems later in life. The study is significant because, according to the International Diabetes Foundation, the leading cause of death among both type 1 and type 2 diabetics is cardiovascular disease as a complication of diabetes.

The study signals a new way of considering how insulin interacts with food. Typically, fast-acting insulin is taken before or with a meal and the amount taken is synched to the carbohydrate content of the meal. But, according to Campbell, that’s not the only impact that insulin has on the food a person eats. And, he learned of this in the most straightforward way possible.

“Originally, I came across this when I was out to dinner with a friend who has type 1 diabetes,” Campbell said. “In addition to their usual insulin dose, they took a second dose of insulin after the meal and it was timed and taken to account for the fat content in the meal, in addition to the carbohydrate content.”

Campbell, who specializes in researching nutrition and diabetes, was intrigued by his dinner companion’s dosing regime. But, when taking a closer inspection of what had previously been researched—the implications of postprandial insulin (that is, insulin taken after eating) and how it impacted metabolizing fat in the bloodstream—he was surprised to find that there very little information to support such a dosing strategy.

The topic of postprandial insulin was not something unknown to Campbell, and not only because he was an expert in nutrition and diabetes. A small study in 2016 again by Campbell found that a bolus injection of rapid-acting insulin three hours after a meal high in carbs and fat prevented hyperglycemia—or high blood sugar—as well as preventing hypoglycemia compared simply by taking insulin before a meal and counting only carbs.

That study was not typical, Campbell says. That’s because fat content in food is not often talked about when researchers and caregivers educate people with diabetes on how to administer insulin to control their blood sugar before, during, and after meals.

“Many people with type 1 diabetes struggle to regulate their blood sugar levels around mealtimes, because the fat content in their food is metabolized after their standard insulin injection has lost its potency or has left their blood,” Campbell says. This led him to move on from the study in 2016 to investigating the role of fat content and insulin and how it impacts cardiovascular health. “Most meals in a typical UK diet have a high fat content, and slower metabolism of this fat can lead to raised blood sugar levels—with risk of hyperglycemia—and also higher levels of fat and inflammatory markers in the blood, which increase the risk of cardiovascular disease.”

For the clinical trial on the effect of insulin on reducing fat and inflammatory markers Campbell tested 10 individuals living with type 1 diabetes. Each of the men were given a low fat meal. The next two meals had the same carb count but were higher in fat. In the first of those two high fat meals, the subjects took a standard pre-meal dose of insulin based on the carb count in the meal. For the second high fat meal the subjects added a dose of one-third of the pre-meal dose of insulin three hours after eating. The blood test six hours after eating that meal revealed glucose, fat, and inflammatory markers that were similar to the levels tested after the low fat meal.

“The insulin three hours after eating was really beneficial,” Campbell says. “What’s more interesting is that even though the sample size was very small, it’s fairly representative of the results we would expect in a larger sample.”

Additionally, the subjects in the test were in good cardiovascular health. That’s also a good indicator because, according to Campbell, people with poorer cardiovascular health may show greater improvements than the ten men in the study demonstrated.

He says the next step will be to do conduct a larger clinical trial of perhaps 1,000 subjects or more to confirm the findings in the small study.

“This is important because it’s something that can be done easily, and directly, by people with type 1 diabetes to improve their own health,” Campbell says. “It only involves making a subtle adjustment, and not a huge, crude change, to how people are already treating their diabetes. And that little change can save lives, and improve quality of life.”

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