Worldwide it’s estimated that 1.7 billion people are overweight according to their body mass index, or BMI. In the United States of America alone 2/3 of the population is overweight, and half of those people are obese. As obesity continues to rise so does one particular disease, Type II Diabetes (T2D). It’s no coincidence that their rise coincides, but to begin understanding the link we must first understand insulin resistance.
The organ responsible for the production of insulin is the pancreas. Insulin’s primary responsibility is to transport sugar from the blood to cells all over the body to either use or store as energy. However, as an individual’s weight increases, the body’s ability to recognize its own insulin diminishes. This phenomenon is called insulin resistance. Further to this the current body of research shows that fat tissue significantly more resistant to insulin than muscle. Therefore, when a person has more fat than muscle, the resistance to insulin (especially over time), allows blood sugars to remain unhealthily elevated.
Genetic factors aside, there are other factors that contribute to insulin resistance: age, medications, ethnicity are a few along with lifestyle behaviors such as activity level, alcohol consumption, tobacco use and even stress levels. It’s not ironic (or coincidental) that these factors are also used to assess one’s risk for being overweight or obese. The combinations of all of these factors together lead to insulin resistance, but is one more predictive than another? The answer is yes: body weight. Body weight is the top predictor of insulin resistance. Being overweight or obese exponentially increases the risk of developing T2D, which is clinically relevant considering 90% of patients with T2D are overweight or obese.
So how does obesity, or rather adiposity (where one’s stored fat is located) contribute to T2D? Patients with a BMI greater than 30 are 80 times more likely to develop T2D than their healthy-weight counterparts. When looking at how fat tissue is stored, where it’s stored is a factor to predicting T2D. Visceral fat, or fat around the organs (opposed to subcutaneous fat found under the skin) poses the greatest risk in the development of T2D. In fact, people with excess abdominal adiposity are more likely to develop T2D, as the fat that’s stored releases inflammatory biomolecules that inhibit the body’s ability to utilize insulin, connecting back to insulin resistance.
At the end of the day what’s important is that we keep our weight in check. When it comes to T2D and the risks of developing the disease, we have some control in our fate. Making good choices when it comes to food, lifestyle and behaviors are all things that we can control. It doesn’t mean we need to be perfect all the time, the fittest person or the one running marathons. What it does mean is that in order to live longer and more healthful lives we must manage our disease risk.