Until recently, type 2 diabetes and heart disease have affected older adults almost exclusively. But the obesity epidemic in America is now putting younger adults at risk for life-threatening diseases that were once rare in those under age 50. Type 1 diabetes, in which the body does not produce insulin, is traditionally seen in children and adolescents. But over the last decade, type 2 diabetes—formerly known as adult-onset diabetes—has increased by 70 percent in adults aged 30 to 39, reflecting, researchers say, the 70 percent increase in obesity in adults aged 18 to 29. In this form of diabetes the body's use of insulin is somewhat impaired.

A recent American Diabetes Association–funded study has found that type 2 diabetes is more aggressive when it occurs in adults 18 to 44 than when it is acquired in older adults. Complications of diabetes include heart attack and stroke, and the study found that younger adults with diabetes are 14 times more like to have a heart attack and 30 times more likely to have a stroke than other people their age.

In the study, published in the November issue of Diabetes Care, researchers examined the medical records of 7,844 members of a health maintenance organization who had been diagnosed with type 2 diabetes and compared them with members who did not have diabetes. Below, lead study author Teresa Hillier, MD, an endocrinologist and investigator at Kaiser Permanente Center for Health Research in Portland, Oregon, discusses how diabetes is different in younger adults, and how Americans can put a stop to this dangerous trend.

Why are younger adults getting type 2 diabetes?
The main reason is that up until a decade or so ago, it was pretty rare to see type 2 diabetes in young adults, and that has changed dramatically with the increasing obesity in our population. People have a genetic risk for type 2 diabetes, but obesity essentially brings that out at a younger age.

The metabolic syndrome, a risk factor for diabetes that includes a constellation of factors such as abnormal glucose (sugar) levels, high cholesterol and high blood pressure, are all worsened by obesity.

Being overweight or being inactive affect how your body processes insulin, so modest weight loss or moderate changes in activity level will improve how insulin works.

Did the term "type 2 diabetes" replace "adult-onset diabetes" because it's becoming more common at younger ages?
Yes, exactly. It's been called non-insulin dependent in the past, but that's not true, either, because although people often start out treating their diabetes with diet and pills, they may need to go on an insulin. And then it was called adult-onset to distinguish it from the kind of diabetes that more typically presents in kids.

Because we're now seeing diabetes in younger people, they've tried to distinguish between type 1 versus type 2. Type 1 occurs when you lose your ability to make any insulin. Everyone with that illness requires insulin from the start. In type 2, which is what 95 percent of the people with diabetes have, there's a relative insulin deficiency; you make insulin, but it's not enough or it doesn't work well enough to have you store the sugar from your meals into your fat and muscle cells.

How was diabetes different in young adults?
It was more aggressive from a heart standpoint. There are several types of complications that occur with diabetes. There is what's called the microvascular complications, which affect the small blood vessels, and can cause blindness or kidney failure or loss of sensation that can lead to amputation in some people with diabetes.

The macrovascular disease affects the large blood vessels, and can cause heart disease and stroke. More than half the people with type 2 diabetes die from the consequences of macrovascular disease. And while the microvascular complications are important, what we're trying to prevent in type 2 diabetes is cardiovascular disease.

So it's the macrovascular disease where we saw the main differences between younger and older adults. Although the absolute rates of heart disease in older people with or without diabetes are still higher, what we really wanted to know was how diabetes is affecting this risk.

We did that by comparing people with new-onset diabetes and looking at their risk of developing a heart attack or a stroke or of needing procedures for a heart attack such as coronary bypass surgery. We compared this group to people without diabetes who were the same age and gender.

What we found was that young adults 18 to 44 with diabetes had a 14-fold higher rate of heart disease compared to their peers, whereas in older adults, that ratio was 4-fold higher. And so that's what we're saying about it being more aggressive.

Similarly, for strokes, we found that up to 30 times higher in young adults versus their peers and, in older adults with diabetes, strokes were 3-fold higher than among their peers.

So people at a younger age aren't getting heart attacks or strokes unless they have diabetes.

Did the two age groups require different treatment strategies?
Although younger and older adults, on average, required treatment after the same amount of time, there were a lot more people in the younger group who needed insulin. People with the early onset were 80 percent more likely to begin insulin therapy.

The reason that you need insulin that is eventually the pancreas kind of burns out and it's not able to keep up with making insulin, so the pancreas is losing it's ability to do that more quickly in younger adults. So that's another reason why it's more aggressive.

How can clinicians distinguish between type 1 and type 2, now that so many young adults have type 2?
That is becoming a more complex issue, too, and there's more studies trying to figure that out. For example, being thin used to be one of the ways we could say this person was a type 1. But now, because so much of our population that is overweight, when someone presents and needs insulin, they could be overweight and still have type 1.

Similarly, some of people with type 2 look like a type 1, and then end up being more like a type 2 and not needing insulin all the time after diagnosis. There's a federal project that is trying to look the differences between type 1 and type 2 diabetes in children.

How can young people reduce their risk for type 2 diabetes?
We have a lot of good information about that now from the Diabetes Prevention Program, a major clinical trial comparing diet and exercise with medical treatment. For people who are high risk for diabetes, the lifestyle changes such as being more active and maintaining a healthy body weight are key. If people are overweight, even a modest weight loss of five to ten pounds can make a big difference.

As much as our study is important for understanding the treatment of type 2 diabetes, I think it's also important for the public in terms of realizing that obesity and type 2 diabetes occurring at an early age is really bad. We need to look a lot more at prevention as a society and realize that our obesity epidemic is not just a cosmetic problem.

How can parents help their children develop habits that will help them avoid a diabetes diagnosis?
I think the parents can set an example by being active and encouraging the kids to be active most every day in some way. This can be done with exercise and activities they like. They should also try to have good eating habits—eating fruits and vegetables and limiting things like soda pop and fruit juice and fast food to special occasions.

It's not only the parents, there are things communities and schools can do. A lot of schools have cut out physical education because they don't have funding for it, but we need to find ways that kids can be active during school. We need to find ways to make it easy for people to be active by walking or riding their bikes places rather than always driving their kids.