Research shows that waistline measurement is a good indicator of diabetes risk and is generally more accurate than body mass index (BMI) readings, says Lydia Kaume, nutrition and health education specialist for University of Missouri Extension.

“This is because belly fat deposited around the waist invades the spaces between our organs, causing insulin resistance. Insulin resistance causes pre-diabetes and diabetes,” Kaume says.

Waist size

According to the National Institutes of Health, a waist size greater than 35 inches for women or greater than 40 inches for men increases your risk for diabetes, she says. To correctly measure your waist, stand and place a tape measure around your middle, just above your hipbones. The tape measure will usually pass within an inch or so of your belly button. Measure your waist just after you breathe out.

Insulin resistance and belly fat

Insulin, a hormone made by the pancreas, moves glucose or sugar generated from the food we eat out of the bloodstream and into the body’s cells, where it is either burned for immediate energy or stored for later use.

When we have insulin resistance, there are problems with the cell preventing sugar from entering. This causes the pancreas to produce more and more insulin to solve the problem. Our blood sugar may gradually stay higher than normal.

Scientists believe that belly fat increases insulin resistance because of its proximity to the portal vein, which carries blood from the intestinal area to the liver, Kaume says. Substances released by belly fat (visceral fat), including free fatty acids, enter the portal vein and are transported to the liver. Studies show that waistline measurements are directly linked with higher levels of total cholesterol and LDL (“bad” cholesterol), lower levels of HDL (“good” cholesterol), and insulin resistance/diabetes risk, she says

Studies also demonstrate that a healthy fat tissue acts as an active “organ,” releasing a variety of bioactive proteins into our blood circulation. One of these important proteins is adiponectin. Adiponectin increases fat breakdown to release energy, which lowers the number of free fatty acids in the blood, and improves our cells’ response to insulin. However, excessive storage of fat, especially around the organs, reduces the amounts of adiponectin produced, increasing our risk for insulin resistance and other health problems.

Other risk factors

According to the American Diabetes Association, 1 in 3 American adults have pre-diabetes. In addition to lifestyle, the following increase our risk for insulin resistance/pre-diabetes and diabetes.

Age. While we can't stop the aging process, you can take certain steps to reduce your risk by staying active, eating a healthy diet, maintaining a healthy weight and keeping your blood pressure under control.

Family history. If a parent, sister or brother has been diagnosed with Type 2 diabetes, there is higher risk for family members. To prevent or delay pre-diabetes, we need to exercise and maintain a healthy weight.

Ethnicity. Pre-diabetes and Type 2 diabetes are more common among African Americans, Hispanics/Latinos, American Indians, Asian Americans and Pacific Islanders.