On average, people with type 1 diabetes die 11 to 13 years earlier than people without the condition, according to a new study from Scotland.

While the news may be disheartening for people with type 1 diabetes, the study’s senior researcher said the new results are more encouraging than previous estimates that found larger gaps in life expectancies.

An important message is that the difference in life expectancy is narrowing, said Dr. Helen Colhoun of the University of Dundee School of Medicine in Scotland.

“It’s not zero,” she said. “The goal is to get it to zero.”

Among people with type 1 diabetes, formerly known as juvenile diabetes, the body’s immune system destroys insulin-producing cells in the pancreas. Insulin removes sugar from the bloodstream so it can be used for energy.

Instead, those people need to inject insulin and pay special attention to their blood sugar – or glucose – levels. Untreated, type 1 diabetes can lead to heart, blood vessel, kidney, eye, and nerve damage.

About 29.1 million Americans have diabetes, according to the Centers for Disease Control and Prevention. About 5 percent of those have type 1 diabetes.

The researchers write in JAMA that according to earlier data from the U.K., people there with type 1 diabetes died an average of 15 to 20 years earlier than nondiabetics. A 1970s report put the decrease in life expectancy at 27 years for type 1 diabetics in the U.S., and a 1980s report from New Zealand put it at 16.5 years.

“They’re mostly very old,” Colhoun said of the estimates. She said the correct information is important, because it shows how far care for type 1 diabetes has come.

For the new study, the researchers used national data from Scotland on 24,691 people diagnosed with type 1 diabetes from 2008 to 2010.

From that data, they estimated that men with type 1 diabetes would live about 11 fewer years than men without the condition. Women with type 1 diabetes would live about 13 fewer years than those without the condition.

At age 20, for example, people with type 1 diabetes could expect to live, on average, to age 66 (for men) or 68 (for women). Those without type 1 diabetes, however, would on average live to ages 77 (for men) or 81 (for women).

Even among people with type 1 diabetes and preserved kidney function, who presumably took care of themselves, there was still about an eight year gap in life expectancy, the researchers found.

“It’s important to stress that these are averages,” said Colhoun. “Some people with type 1 diabetes will achieve a very long life expectancy and some people will have a short life expectancy. These are estimates.”

Overall, the largest contributer to loss of life expectancy was heart disease. People who died younger than age 50 were more likely to die of more short-lived problems, however. Those include diabetic comas and ketoacidosis, which is when the body begins to break down fat and starts producing toxic acids.

Colhoun said the new results emphasize the need for people with type 1 diabetes to have tight control of their blood sugar levels. Additionally, they should control their risk factors for heart disease.

“For type 1 diabetes, the key thing is really glycemic control, because it in turn determines your kidney health – for example – which in turn has a big impact on cardiovascular health,” she said.

In a second study in the same journal, researchers compared 711 people who maintained tight control over their blood sugar levels for seven years, with 730 people who did not maintain rigorous control over their sugar levels.

Overall, people who maintained tight control over their blood sugar were less likely to die over 27 years, compared to those who did not.

“It provides optimism that while we don’t have a way to cure diabetes, at least we have a way to preserve health and the futures of people with type 1 diabetes,” said Dr. Lori Laffel of the Joslin Diabetes Center in Boston.

As for the paper from Scotland, Laffel, who co-authored an editorial accompanying the new studies, said it shows how much better life expectancy is, compared to previous estimates.

There's ongoing research to implement current tools and future advances to narrow the gap to zero, she said.