Ninety years ago, type 1 diabetes was a death sentence: half of people who developed it died within two years; more than 90% were dead within five years. Thanks to the introduction of insulin therapy in 1922, and numerous advances since then, many people with type 1 diabetes now live into their 50s and beyond. But survival in this group still falls short of that among people without diabetes.
A Scottish study published this week in JAMA shows that at the age of 20, individuals with type 1 diabetes on average lived 12 fewer years than 20-year-olds without it. A second study in the same issue of JAMA showed that people with type 1 diabetes with better blood sugar control lived longer than those with poorer blood sugar control.
Types of diabetes
There are three main types of diabetes:
Type 1 diabetes is an autoimmune disease. The immune system mistakenly attacks and destroys cells in the pancreas that make insulin. This usually happens before age 20. Insulin is needed to get blood sugar (glucose) into cells for energy. Without insulin, glucose builds up in the bloodstream. This damages cells and tissues throughout the body. People who develop type 1 diabetes need to take insulin via shots or a pump for life.
Type 2 diabetes tends to occur later in life, usually among individuals who are overweight or inactive. It accounts for about 90% of all diabetes. People with type 2 diabetes often make enough insulin, at least at first, but their cells don't respond to it. As with type 1 diabetes, glucose builds up in the bloodstream, damaging cells and tissues throughout the body. Type 2 diabetes is initially treated with lifestyle changes such as weight loss, more exercise, and a healthier diet. Medications that make the body more sensitive to insulin and do other things to control blood sugar may also be needed.
Gestational diabetes develops during pregnancy, and fades away after delivery. About 1 in 20 women develop gestational diabetes.
Living with type 1 diabetes
Insulin can be a difficult drug to manage. A mismatch between insulin and food intake can cause blood sugar to drop dangerously low (hypoglycemia). This can lead to symptoms such as a fast heartbeat or feeling shaky. It can cause diabetic ketoacidosis, in which the body's chemical balance becomes deranged because there's not enough insulin to move sugar into cells. Hypoglycemia can also lead to a diabetic coma, and even death. In the Scottish study, 21% of deaths among younger people (under age 50) with type 1 diabetes occurred as a result of diabetic coma and related causes.
That said, insulin works very well for most people with type 1 diabetes. Other reasons why people with type 1 diabetes are now living longer include:
Better insulins are available, and they are easier to use. Some last all day, others work very quickly. Insulin pumps make it easier to deliver insulin
Better ways to track blood sugar with home glucose monitors and even continuous glucose monitors. Keeping blood sugar close to normal is linked with longer life.
New drugs and other therapies to prevent and treat complications of diabetes, such as heart disease and kidney disease. Both are major causes of early death in people with type 1 diabetes.
The second JAMA study was a long-term follow-up of men and women who participated in the Diabetes Control and Complications Trial, which ran from 1983 to 1993. Half were assigned to "tight" blood sugar control. They aimed to keep hemoglobin A1c (HbA1c), a measure of blood sugar control, under 7%. (People without diabetes have HbA1c levels of 5% or lower.) Those assigned to "conventional" blood sugar control averaged 9% on the HbA1c. After 27 years, participants in the tight control group were less likely to have died than those in the conventional control group.
This suggests that tight control is one way to improve survival in people with type 1 diabetes. That makes sense because lower blood sugar means less damage to cells and tissues. But it may also mean more brushes with hypoglycemia, which poses its own set of problems.
Not everyone with diabetes should strive for near-normal blood sugar levels. For example, people who are older, or frail, or who have other health issues may not be good candidates for tight blood sugar control.
Beyond blood sugar control, keeping cholesterol and blood pressure in the healthy range is essential for people with diabetes.
Back in 1948, the Harvard-affiliated Joslin Clinic in Boston began giving Victory Medals to individuals who had lived with type 1 diabetes for 25 years. The program was expanded in 1970 with 50-year medals. The first 75-year medal was presented in 1996.
In addition to honoring long-term survivors, investigators at the Joslin Diabetes Center are studying them to learn what has helped them beat the odds. This work, and other research around the United States and the world may help further extend life for people with type 1 diabetes.