Causes of Type 2 Diabetes

Causes of Type 2 Diabetes
Eating too much and exercising too little are two of the main reasons why people develop type 2 diabetes.
By Madeline Vann, MPH
Medically reviewed by Christine Wilmsen Craig, MD Print Email Insulin is a hormone made in the pancreas that allows glucose (sugar) to leave the bloodstream and enter the cells to be used as fuel. Type 2 diabetes occurs when the pancreas doesn't make enough insulin or the cells of the body become resistant to insulin. It is not known for certain why some people develop type 2 diabetes and some do not; however, there are several factors, such as genetics, obesity, and physical inactivity, that can increase a person's risk of developing type 2 diabetes.

Type 2 Diabetes: Primary Causes

Being obese or overweight puts you at significant risk for developing type 2 diabetes. Four out of five people with type 2 diabetes are overweight or obese.

“One of the links with obesity is that fat induces a mild, low-grade inflammation throughout the body that contributes to heart disease and diabetes,” says Vivian Fonseca, MD, professor of medicine and pharmacology and chief of endocrinology at Tulane University Health Sciences Center in New Orleans.

Excess fat, especially abdominal fat, also changes the way that your body responds to insulin, leading to a condition called insulin resistance. With this condition, your cells cannot use insulin to process blood sugar out of the blood, resulting in high blood sugar levels. While not everyone with insulin resistance develops diabetes, people with insulin resistance are at increased risk of type 2 diabetes.

Type 2 Diabetes: Poor Eating Habits
Eating too much of the wrong kinds of foods can increase your risk of type 2 diabetes. Studies have shown that eating a diet of calorie-dense, refined foods and beverages, such as sodas or fruit juices, and too little raw fruits, vegetables, and whole grains can significantly increase your risk of type 2 diabetes.

Type 2 Diabetes: Too Much TV Time

An analysis of health and nutrition data from a nationally representative sample of adults between the ages of 20 and 54 years of age showed that people who watched television more than two hours a day were more likely than their peers to be obese and to have diabetes. This is probably due to snacking while watching TV. The study found that the frequent TV watchers consumed, on average, 137 more calories a day than their peers. Conversely, the data indicated that cutting TV time back to less than 10 hours a week and adding a daily 30-minute walk led to 43 percent fewer cases of diabetes in the study group.

Type 2 Diabetes: Physical Inactivity

Just as body fat interacts with insulin and other hormones to affect diabetes development, so does muscle. Lean muscle mass, which can be increased through exercise and strength training, plays a role in protecting the body against insulin resistance and type 2 diabetes. A six-month study of 117 older men and women with abdominal obesity recently demonstrated that a mix of aerobic and resistance training exercises helped to reduce insulin resistance.

Type 2 Diabetes: Sleep Habits

Sleep disturbances have been shown to affect the body’s balance of insulin and blood sugar by increasing the demand on the pancreas. Over time, this can lead to type 2 diabetes. An analysis of data from 8,992 adults who participated in the First National Health and Nutrition Examination Survey showed that over the course of a decade, those who slept fewer than five hours a night or more than nine were at increased risk of type 2 diabetes.

Type 2 Diabetes: Genetics

Genes play an important role in determining a person's risk of type 2 diabetes. Researchers have identified at least 10 genetic variations linked to increased risk for this disease. However, your genes are not your fate; diet and exercise can prevent type 2 diabetes even if you have family members with the condition.