Diabetes is on the Rise in People of Normal Body Weight – but Why?
Type 2 diabetes is more common in people who are overweight or obese, no surprise here. In fact, that’s a risk of gaining weight, that you’ll become insulin resistant and eventually develop full-blown type 2 diabetes. Having a high body fat percentage makes insulin resistance more likely, especially if you’re genetically predisposed. Yet, being of normal body weight is no guarantee that you won’t develop type 2 diabetes. In fact, a new study shows insulin resistance, what we think of as “prediabetes” is on the rise in people who aren’t overweight or obese. The question is why?
Prediabetes is a condition where your fasting blood sugar is higher than normal but not yet in the range that constitutes diabetes. Being in this “in-between” range usually means you’re insulin resistant, yet, your pancreas is still doing a marginally good job at producing enough insulin to keep your blood sugar from rising into the diabetic range. If you’re prediabetic, your fasting blood sugar is between 100 to 125. About 79 million American fall into this category.
Yet, the number of people with prediabetes used to be lower. When researchers looked at data from the U.S. National Health and Nutrition Examination surveys carried out from 1988 to 1994 and again from 1999 to 2012, they made some interesting observations. In the 1988 survey, around 10% of people of normal body weight had prediabetes. However, when they looked at results from the second survey that began in 1999 and ended in 2012, the percentage had risen to 18.5%. The percent of people with prediabetes also increased in men and women over the age of 45 from 22% to 33%. For some reason, the percentage of people who aren’t obese or overweight with prediabetes is significantly higher from one survey to the next – but why?
You Can Get Diabetes if You’re of Normal Weight
You might think if your weight is in the normal range, your risk of prediabetes is pretty low. Yes, it’s lower than the risk of someone who is obese, but, as we see from this survey, body weight isn’t the only factor. Something else is driving the increase. Of course, genetics are an issue. If you have a strong family history of type 2 diabetes, your risk may be higher than the average person even if you keep your weight within a normal range.
Age is another factor. As you grow older, insulin sensitivity goes down and your cells become less responsive to the insulin your pancreas makes. As a result, your pancreas has to produce more insulin to get glucose into cells. Soon, you have chronically high levels of insulin as your pancreas works overtime to pump out more and more. Eventually, it can’t keep up with the demand and your blood sugar begins to rise above the normal range, but not yet to the diabetic range. That’s prediabetes. Prediabetes is more common after the age of 40.
Evidence also suggest that factors like stress and, possibly, chronic low-grade inflammation may be underlying factors in prediabetes. Stress stimulates the release of cortisol, a hormone that causes a rise in blood sugar.
The question still is why has the incidence of prediabetes risen in people who aren’t overweight or obese? Genetics probably aren’t the explanation since genes that regulate blood sugar and insulin sensitivity haven’t changed much over a few decades. Consumption of high-glycemic foods, refined carbs, and soft drinks have increased slightly but people were drinking soft drinks and eating processed foods in the late 1980’s and mid 1990’s when they did the first survey. So, there may be another explanation.
Are Changes in Body Composition a Factor?
Body weight isn’t a reliable measurement of health. In fact, there’s a growing epidemic of normal-weight obesity, being of normal weight, yet having a body fat percentage that’s too high. People who suffer from normal-weight obesity are more likely to be inactive and not resistance train. Partially because they’re inactive, they lose muscle faster as they age as they also gain body fat. The result is a body fat percentage that’s “obese,” despite registering a normal body weight and BMI. These individuals simply have too little muscle relative to body fat. This can be true even if you’re not overweight or obese. Having a high percentage of body fat relative to muscle like being overweight or obese places you at higher risk of prediabetes and diabetes. So, lack of physical activity and normal-weight obesity is another possible explanation for the increase in prediabetes.
Why is Prediabetes a Problem?
Prediabetes is a warning sign that you’re on the path to type 2 diabetes. Without making changes, you have a significant risk of developing type 2 diabetes over the next decade. What’s more concerning is changes to your heart and blood vessels can happen at the prediabetes stage, even before you develop type 2 diabetes. So, your risk of heart disease goes up.
There’s something else to keep in mind. Research shows a significant number of Americans who have prediabetes are not being treated for it and don’t know they have it. Always ask your doctor what your fasting blood glucose level is rather than assuming it’s alright if they don’t say anything.
Another blood test called a hemoglobin A1C test is a better measure of what your blood sugars have been over the past three months. It provides additional information that a single fasting blood sugar measurement doesn’t and is a better test for prediabetes or diabetes. Normally, your hemoglobin A1C should be 5.6% or less. You rarely have symptoms with prediabetes, so don’t assume because you feel okay that your blood sugars are normal. Prediabetes is a silent health problem.
The Bottom Line
Now you know that you can develop prediabetes (or diabetes) if you’re not overweight and that the number of people who fall into this category is greater than it used to be. You also recognize that body weight is deceptive. It says nothing about your body composition, how much muscle relative to fat you have. If you have a high body fat percentage and little muscle, you may be metabolically unhealthy even if your body weight is normal. The way to improve your metabolic health is to do resistance training to preserve your lean body mass and lose body fat and eat a whole, unprocessed diet. Doing these things is no guarantee that you’ll never develop prediabetes but it will greatly lower your risk.
Ann Fam Med. 2016;14(4):304-310. doi: 10.1370/afm.1946.
WebMD. “What is Prediabetes?”
Cardiology Advisor. “Prediabetes Has Increased in Adults With Normal BMIs”
Cardiology Advisor. “Study Suggests Doctors Miss Opportunities to Treat Prediabetes”
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