Causes and Risk Factors of Type 2 Diabetes

Researchers don't know what causes type 2 diabetes, but they believe several factors are at play. Those factors include genetics and lifestyle, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). (7)

At the root of type 2 diabetes is insulin resistance, and prior to a type 2 diabetes diagnosis, you may be diagnosed with prediabetes, notes the NIDDK. (8)

Insulin Resistance

Type 2 diabetes is marked by high blood sugar that your body can’t bring down on its own, according to the NIDDK. High blood sugar is called hyperglycemia; hypoglycemia is low blood sugar. (8)

Insulin — the hormone that allows your body to regulate sugar in the blood — is made in your pancreas. Essentially, insulin resistance is a state in which the body’s cells do not use insulin efficiently. As a result, it takes more insulin than normal to transport blood sugar (glucose) into cells, to be used immediately for fuel or stored for later use. A drop in efficiency in getting glucose to cells creates a problem for cell function; glucose is normally the body’s quickest and most readily available source of energy, notes the NIDDK. (8)

Insulin resistance, the agency points out, doesn’t develop immediately, and often, people with the condition don’t show symptoms — which may make getting a diagnosis tougher. (8)

As the body becomes more and more insulin resistant, the pancreas responds by releasing an increasing amount of insulin. This higher-than-normal level of insulin in the bloodstream is called hyperinsulinemia, per the NIDDK. (8)

Prediabetes

Insulin resistance sends your pancreas into overdrive, and while it may be able to keep up with the body’s increased demand for insulin for a while, there is a limit to insulin production capacity and eventually your blood sugars will elevate — leading to prediabetes, the precursor of type 2 diabetes, or type 2 diabetes itself, according to the NIDDK. (8)

A prediabetes diagnosis doesn’t mean you’ll definitely develop type 2 diabetes. Catching the diagnosis quickly and then changing your diet and lifestyle can help prevent your health from worsening, the agency adds. (8)

QUIZ: Are You at Risk for Type 2 Diabetes?

Prediabetes and type 2 diabetes are some of the most prevalent diseases in the world — altogether affecting 100 million Americans, according to the CDC. Nontheless, according to an article published in June 2016 in Current Cardiology Reports, researchers still aren’t completely sure which genes cause insulin resistance. (8,9)

Type 2 Diabetes Risk Factors

As mentioned, type 2 diabetes is a multifactorial disease. That means you can’t just stop eating sugar or start exercising to avoid developing this health condition.

Here are some of the factors that may affect your risk of developing type 2 diabetes:

Obesity Being obese or overweight puts you at significant risk for developing type 2 diabetes. Body mass index (BMI) determines whether you are obese or overweight, according to the National Heart, Lung, and Blood Institute (NHLBI). (10)

Poor Eating Habits The American Diabetes Association (ADA) emphasizes that eating too much of the wrong kinds of foods can increase your risk of type 2 diabetes. (11) Studies have shown that eating a diet high in calorie-dense, processed foods and beverages, and low in whole, nutrient-rich foods, can significantly increase your risk of type 2 diabetes. Foods and drinks to limit include white bread, chips, cookies, cake, soda, and fruit juice. Foods and drinks to prioritize include fruits, veggies, whole grains, water, and tea.

Too Much TV Time The Harvard T.H. Chan School of Public Health notes that watching too much TV (and sitting too much in general) may increase your risk for obesity, type 2 diabetes, and other ailments. (12)

Not Getting Enough Exercise According to John Muir Health, just as body fat interacts with insulin and other hormones to affect diabetes development, so does muscle. (13) Lean muscle mass, which can be increased through cardiovascular exercise and strength training, plays a role in protecting the body against insulin resistance and type 2 diabetes.

Sleep Habits Sleep disturbances can affect the body’s balance of insulin and blood sugar by increasing the demand on the pancreas, the National Sleep Foundation points out. (14) Over time, this can lead to type 2 diabetes.

Polycystic Ovarian Syndrome (PCOS) By some estimates, a woman diagnosed with PCOS — a hormone imbalance disorder — has a greater risk of developing type 2 diabetes than her peers without PCOS, according to a study published in August 2017 in the Journal of Clinical Endocrinology & Metabolism. (15) Insulin resistance and obesity are common denominators of these health conditions.

Being Over Age 45 The older you get, the more likely you are to develop type 2 diabetes, per the ADA. (16) But in recent years, an increasing number of children and teens have been diagnosed with prediabetes and type 2 diabetes.

Is Type 2 Diabetes Genetic?

Independent of diet and lifestyle factors, your genetics can affect your risk for type 2 diabetes, too.

Research on twins backs this up, according to an article published in December 2013 in the British Journal of Clinical Pharmacology. (17) Twins who are identical are more likely to both have diabetes compared with twins who are fraternal. And having a relative with diabetes may put you at a fourfold risk of developing the disease yourself.

Your ethnicity or race may affect your risk for type 2 diabetes, too, noted an article published in December 2013 in Current Diabetes Reports. (18) Data included in this paper suggests African Americans, Hispanic or Latino Americans, and certain Native American groups have a higher risk of type 2 diabetes than Caucasians.