The actual cause of diabetes depends on the type of diabetes you have. To some extent, it’s not always clear to doctors what causes a patient’s diabetes. Some factors that increase your risk for diabetes are outside of your control, like age and ethnicity. Still, there are ways you can lower your risk for Type 2 diabetes.
Here are the causes of Type 1 and Type 2 diabetes.
Type 1 diabetes is considered an autoimmune disease. With an autoimmune disease, your immune system – which helps protect your body from getting sick – is engaged in too little or too much activity. In Type 1 diabetes, beta cells, which are a kind of cell in the pancreas that produces insulin, are destroyed. Our bodies use insulin to take the sugar from carbohydrates we eat and create fuel. With Type 1 diabetes, your body does not produce insulin, and that’s why you need to use insulin as part of your treatment.
Type 1 diabetes has some connection to your family genes, but that doesn’t mean you’ll get it if one of your parents had it. “Since not all identical twins get diabetes, we do think that exposure to an additional environmental factor may trigger an immune response that ultimately causes destruction of the insulin-producing cells of the pancreas,” says Dr. Sarah R. Rettinger, an endocrinologist with Providence Saint John’s Health Center in Santa Monica, California.
Researchers are still trying to understand the exact causes of Type 1 diabetes, according to the National Institute of Diabetes and Digestive and Kidney Diseases.
Type 1 diabetes is more common in children and teens, but it can also occur in adults. It often comes about suddenly. “Unfortunately, there’s no way to prevent Type 1 diabetes,” Rettinger says.
Type 2 diabetes is caused by a complicated interaction of genes and the environment, Rettinger says.
“We know that there is a very large genetic component,” Rettinger says. “A person with a first-degree relative with Type 2 diabetes has a five to 10 time higher risk of developing diabetes than a person the same age and weight without a family history of Type 2 diabetes.” Heredity actually plays a larger role in Type 2 diabetes than Type 1, Rettinger says.
When you have Type 2 diabetes, you may start out with something called insulin resistance. This means your cells do not respond well to the insulin you are making. “Insulin levels may be quite high, especially in the early stages of the disease. Eventually, your pancreas may not be able to keep up, and insulin secretion goes down,” Rettinger explains. Insulin resistance becomes more common as you put on more weight, especially weight around your belly.
“Insulin resistance is the major link to Type 2 diabetes,” says Dr. Dennis Gage, an endocrinologist with Park Avenue Endocrinology & Nutrition in New York. “Stress, infection and any environmental factor that causes stress will cause insulin resistance and increase the development of Type 2 diabetes.”
A growing number of people in the U.S. and throughout the world are overweight and more prone to develop Type 2 diabetes, particularly if they have the genetics for it. “Type 2 diabetes can be caused by genetic inheritance, but by far the obesity epidemic has created massive increases in the occurrence of Type 2 diabetes. This is due to the major insulin resistance that is created by obesity,” Gage says.
With such a surplus of food nowadays, it’s easy to overindulge without physical activity, leading to weight gain and, for some people, eventual Type 2 diabetes. “It’s a lack of exercise and still eating like you’re 20 years old,” says Susan M. De Abate, a nurse and certified diabetes educator and team coordinator of the diabetes education program at Sentara Virginia Beach General Hospital.
However, that doesn’t mean everyone who has Type 2 diabetes is overweight. De Abate says her father was always slim and a runner – and yet, he developed diabetes. “I told him, ‘Your pancreas got old,'” she says.
People of certain ethnicities are also more likely to develop diabetes. African-Americans, Mexican-Americans, American Indians, Native Hawaiians, Pacific Islanders and Asian-Americans have higher incidences of diabetes, according to the American Diabetes Association.
Your risk for Type 2 diabetes increases as you get older. It also increases if you smoke. Although smoking doesn’t cause diabetes per se, the negative effects on your health are enough to make it more likely that Type 2 diabetes will occur if you have the other risk factors. “We try to be aggressive with smoking cessation, in particular in patients with diabetes,” says Dr. Asha M. Thomas, an endocrinologist with Sinai Hospital of Baltimore.
Type 2 diabetes is more common in adults, but younger people can get it too. “There’s a rate in children that’s growing by leaps and bounds,” De Abate says. That also ties in with trends in unhealthy eating and lack of exercise.
Type 2 is also the most common type of diabetes, accounting for about 90 percent of all diabetes cases, the World Health Organization reports.
The good news is that you play a role in helping to prevent Type 2 diabetes. “Reducing carbohydrates and total calories combined with exercise of 150 minutes or greater per week are recommended as a prevention for Type 2 diabetes,” Gage says.
“Poor diet, weight gain and a sedentary lifestyle – these are largely within our control,” Thomas says.
As always, talk to your doctor if you think you may have diabetes. He or she can help check your blood sugar levels and provide a correct diagnosis. If your blood sugars indicate you have prediabetes – a condition that occurs before Type 2 diabetes – you should be extra vigilant in making changes for healthier living.