Why is Type 2 diabetes becoming a global epidemic, and is it just a coincidence that its rise is joined by another global epidemic — obesity? Could it be that the two are linked in some way, and if so, how? Dr. Nicola Davies, author of I Can Beat Obesity! Finding the Motivation, Confidence and Skills to Lose Weight and Avoid Relapse, investigates.
The role of insulin resistance in the obesity-diabetes link
Understanding insulin resistance is fundamental to answering the obesity-diabetes link question. The pancreas produces insulin, which helps the sugar we eat become fuel for cells in the muscles, fat, and liver to use for energy. Insulin resistance, however, reduces the ability of these cells to use the sugar for energy. This is more likely to occur in people who are overweight or obese since excess fat makes the cells less responsive to insulin, causing insulin resistance. There is also scientific evidence showing that fat cells are more insulin resistant than muscle cells. In other words, insulin is less effective in people who are overweight or obese, causing glucose in the bloodstream to remain high.
There are several contributing factors to insulin resistance, not all of which are weight related. Some can be controlled, while others cannot. Genetics, age, and ethnicity all play a part. Medications like steroids can interfere with the insulin mechanism. Lifestyle factors such as alcohol intake, smoking, exercise level, and stress also play a key role, and there’s a cardiovascular connection too; individuals with high blood pressure and cholesterol are more prone to diabetes.
Yet the one overarching indicator that outshines all other factors in terms of whether you’ll develop insulin resistance is your body weight. Nearly one-third of all American adults are obese, and the number of obese children has tripled in the last four decades. Indeed, obesity is the single best predictor of whether a person will develop Type 2 diabetes. If you are overweight or obese (characterized by a body-mass index [BMI] greater than 30), you have an exponentially higher risk of developing diabetes during your lifetime. In fact, almost 90 percent of people with Type 2 diabetes are overweight or obese.
How obesity contributes to diabetes
People with a BMI above 30 are 80 times more likely to develop Type 2 diabetes than people with a BMI under 22. Why is this? If we look more closely, it isn’t necessarily the weight itself that contributes to diabetes, but where it is stored in the body. Body fat can be classified according to two locations — visceral or subcutaneous.
• Visceral fat is stored inside the belly area and wraps around the walls of internal organs, which means it can’t easily be removed by typical diets or exercise.
• Subcutaneous fat is found right beneath the skin and is what you can physically measure when taking your waist circumference — the so-called “love handles.’”
Visceral fat is the type that increases the risk of developing serious health problems such as diabetes. While subcutaneous fat isn’t as dangerous in general, when it comes to the belly area, both types of fat are present, so a growing belly can be a sign that one or both types of fat are increasing in the stomach region, raising your risk for diabetes.
Ultimately, the weight around the midsection is the type we need to watch when it comes to preventing or controlling diabetes. People with excess abdominal fat (see table below) are much more prone to developing Type 2 diabetes because abdominal fat cells release inflammatory chemicals that reduce the body’s ability to incorporate and utilize insulin.
It isn’t just where body fat (also known as adipose) is stored, but also the type of fat being stored. There are two kinds of adipose (fat) tissues.
• Brown adipose tissues are, as you might expect, dark brown in color. They are linked with many blood vessels and associated with calorie burning, heat production, and energy balance.
• White adipose, on the other hand, is responsible for storing energy and accumulates excessively in obesity. In a healthy body, muscles, fat tissue, and the liver absorb glucose from the bloodstream. White adipose supports this process of glucose regulation, which in turn helps reduce the risk of obesity and diabetes. However, when white adipose becomes excessively thick, its ability to help regulate glucose levels is disrupted.
Understanding fat and how it is stored in the body can be useful if you are embarking on a weight-management regimen to prevent or control diabetes.
The obesity-diabetes link starts young
The risk of developing Type 2 diabetes by age 25 quadruples in obese children. One large study in the United Kingdom examined electronic health records from 1994 to 2013 for nearly 370,000 children ages 2 to 15 for high BMI values indicative of childhood obesity. Researchers then looked at the diagnoses of either Type 1 or Type 2 diabetes up to age 25 in those same people. Obese children had four times the risk of developing Type 2 diabetes by age 25 compared to those children with a normal BMI during childhood.
Historically, Type 2 diabetes had been considered an adult disease, but currently, Type 2 diabetes in children is being diagnosed at an alarming rate, with doctors attributing it to obesity, unhealthy diets, and lack of physical activity. Obesity is also an indicator of childhood Type 1 diabetes. Although Type 1 is an autoimmune disorder, factors such as obesity and insulin resistance further complicate the condition. In one study comprised of nearly 100,000 children who were monitored for weight changes during the first year of life, overweight and obese babies had a positive correlation with increased Type 1 diabetes incidence. The heavier the child, the younger the age of diabetes diagnosis. Although insulin resistance is not the main driver for Type 1 diabetes, this study shows that obesity does play a role and could explain why more children are developing both types of diabetes.
The sleep connection
The link between obesity and diabetes isn’t straightforward because other factors can exacerbate the link. Sleep is one area where this is particularly the case. Sleep is vital to so many of the body’s core functions, including insulin regulation. Untreated sleep issues such as sleep apnea, which is more common in overweight people, can increase the risk of developing obesity, which in turn increases the risk for insulin resistance and Type 2 diabetes.
Abdominal fat and overall obesity are the two biggest risk factors for developing sleep apnea because the excess fat in the pharynx (the part of the throat behind the mouth and nasal cavity) is more likely to block the airways. A cascade effect occurs in that obese people are more likely to develop obstructive sleep apnea, with even moderate sleep apnea disrupting metabolic processes and increasing the risk of developing diabetes.
Endocrinologists point out that poor sleep negatively affects blood sugar levels and also disrupts many other bodily processes like cholesterol and blood pressure. These problems are much worse in obese individuals. Unfortunately, many people with Type 2 diabetes do suffer from poor sleep. Both the quantity of sleep as well as the quality matter in this equation. People who get too little sleep (less than six hours) or too much (more than nine hours) are more prone to Type 2 diabetes. Indeed, a British study of approximately 4,500 children showed that insufficient sleep was associated with three risk factors for Type 2 diabetes: higher BMI, increased insulin resistance, and elevated glucose readings.
Prediabetes and metabolic syndrome
Researchers have another theory that obesity leads to prediabetes, a condition characterized by elevated blood glucose levels that are not high enough to make a diabetes diagnosis. The number of people with prediabetes is rising sharply — at least 84 million people in the U.S. had it in 2015. Over time, prediabetes causes the body’s cells to start losing the ability to uptake insulin. In fact, most people with prediabetes end up developing Type 2 diabetes within 10 years.
Metabolic syndrome, a related condition, is a complex set of risk factors including excess abdominal fat, high blood pressure, elevated triglycerides, low HDL or “good” cholesterol, and high blood sugar levels. Many obese people suffer from this condition, which dramatically raises their chances of developing diabetes, among many other illnesses. In fact, having multiple metabolic syndrome risk factors leads to a five-fold increase in your risk for diabetes.
Metabolic syndrome, also called Syndrome X or obesity syndrome, is hereditary, and as you get older, the risk gets higher. It’s very common among Native Americans, African Americans, Hispanics, and Asians — some of the same ethnicities that are more prone to diabetes. Doctors aren’t sure exactly why metabolic syndrome develops, but two of the biggest indicators are obesity (particularly abdominal fat) and insulin resistance.
What can I do?
Obesity is the single biggest predictor of Type 2 diabetes, but fortunately, even small weight-related changes are very effective. Losing as little as five to 10 percent of your weight has been found to result in drastic improvements in overall health and well-being, which in turn reduce diabetes risk. If you weigh 200 pounds, lose 10 and see what happens. Diet interventions to reduce carbohydrates can be very effective. Get moving too — moderate walking for as little as 20 minutes per day can rev up your metabolism. Studies in which people employed these measures showed as much as a 60 percent reduction in the development of diabetes.
If you already have prediabetes or full-blown Type 2 diabetes, stay focused and stay positive. You can make many lifestyle changes to your diet and exercise routine to prevent the situation from getting any worse. The same measures mentioned above will work even if you’ve already been diagnosed. Indeed, increasing evidence shows that weight loss can actually reverse Type 2 diabetes.
The fact that weight and diabetes are so intertwined is a good thing, even if it might not seem so. It gives many of us some control over how we can avoid or manage diabetes. Indeed, the more we learn about how the link between these two conditions, the more empowered we are to tackle them head on in pursuit of better health and well-being.
Obesity: fact from fiction
• Overweight is the same as obesity
Being overweight is not the same as being obese. Overweight may simply be a result of having heavy bones or muscle mass, or even high body water content, but not necessarily fat. Obesity, on the other hand, refers only to having too much adipose tissue or fat in the body. Both conditions, however, refer to having weight or fat that is in excess of what is considered healthy for your height.
• An ideal weight is a healthy weight
Some people assume that they are unhealthy or “too fat” when their weight doesn’t fall in the ideal range. A healthy weight is computed based on your height, weight, and other factors. On the other hand, your ideal weight is often based on your personal preference and how you want your physique to appear. For obese people, losing five or 10 percent of their weight can already be healthy (or healthier) because it can reduce the risk of developing certain health problems. So, always try to aim for a healthy weight, rather than your ideal weight — they aren’t necessarily the same thing.
• Obesity is detected through shrinking clothes and extra pounds
Some people assume they are overweight or obese when their clothes feel tighter, the scale shows they’ve gained weight, or their waist feels wider than before. Although these signs show that you have gained some weight, they do not automatically mean you are obese.
Interesting fact: the obesity-diabetes-memory link
Type 2 diabetes has been linked to memory loss, and researchers now believe this could be related to increased weight in many people with Type 2 diabetes. People who are overweight or obese have been found to develop thinner grey matter in parts of the brain related to memory. Not only could weight management help with your diabetes, but it could also improve your memory.
Want to learn more about weight and diabetes? Read “Is Bariatric Surgery for You?” “Bariatric Surgery and Type 2 Diabetes: Diabetes Questions & Answers,” and “Strategies for Weight Management.”