Even Modest Physical Activity Helps Prevent Diabetes: New Study
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Even small amounts of exercise can help protect against insulin resistance – a precursor of pre-diabetes and diabetes – tied to the typical American high-fat diet.
That’s the take-home message of a new study published in the Experimental Physiology journal. The research confirms expert recommendations to get in at least 30 minutes of moderate physical activity five days a week to reduce your risk of developing diabetes.
Researchers from the Integrative Muscle Metabolism Laboratory studied the effects of exercise on two groups of mice which were fed a diet mimicking the typical American high-fat diet.
The first group was genetically engineered to have a higher quantity of mitochondria, the tiny structures in cells that convert glucose and fats to energy. Previous research had suggested that increased numbers of mitochondria may help fix some symptoms of a high-fat diet. The second group were not genetically modified in any way.
The mice were then divided into groups, one of which was allowed to exercise and a second remained sedentary.
In both the genetically engineered and normal mice, the researchers found that physical activity – regardless of the amount of mitochondria – offered similar protection against insulin resistance.
They concluded that exercise alone appears to help remove damaged cellular materials and enhance the quality of the mitochondria. This suggests that mitochondrial quality is more important than quantity in the fight against insulin resistance, prediabetes and diabetes.
With rates of obesity and Type 2 diabetes increasing in the U.S. and worldwide, the authors said that understanding the cellular processes that help or hurt insulin resistance can help scientists better tailor effective preventative measures such as exercise.
“For now, physical activity is the greatest protection, but further research may enable us to prevent and treat insulin resistance, and subsequent diabetes, more effectively,” said lead researcher Megan E. Rosa-Caldwell, a doctoral student at University of Arkansas.
According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), insulin resistance is a condition in which muscle, fat, and liver cells do not respond properly to insulin and cannot easily absorb glucose from the bloodstream. As a result, the body needs higher levels of insulin to help glucose enter cells.
To keep up with the demand, beta cells in the pancreas produce more insulin. As long as the beta cells produce enough insulin to counter the insulin resistance, blood glucose levels stay in a healthy range.
Over time, however, the beta cells may no longer be able to meet the body’s increased demand for insulin. Without enough insulin, excess glucose builds up in the bloodstream, leading to prediabetes, diabetes, and other serious health disorders such as heart disease, nerve damage, eye problems, and kidney disease.
In the United States, prediabetes is an increasingly common condition. About 86 million Americans ages 20 and older have prediabetes, according to the NIDDK. Another 29.1 million Americans – 9.3 percent of the population – have full-blown diabetes and one in four are unaware they have the disease.
Although more research needs to be done, most experts believe the major causes of insulin resistance are excess weight and physical inactivity.
Particularly worrisome is excess fat around the waist, a common consequence of an unhealthy diet. Excess belly fat triggers low-level chronic inflammation and produces hormones and other substances that can cause insulin resistance and other serious problems such as high blood pressure, imbalanced cholesterol, and cardiovascular disease.
That’s why experts strongly recommend that men keep their waist circumference under 40 inches and that women keep their waist circumference under 35 inches.
A sedentary lifestyle promotes insulin resistance, prediabetes, and diabetes because inactive muscles don’t burn their stored glucose for energy and refill their reserves with glucose taken from the bloodstream. As a result, blood glucose levels can become dangerously elevated.
The Diabetes Prevention Program (DPP) – a federally funded study of 3,234 people at high risk for diabetes – found that insulin resistance can be prevented or reversed by two lifestyle changes:
- Losing a modest amount of weight (about 5-7 percent of one’s starting weight) by reducing calorie intake, and eating a healthier diet.
- Adopting a modest exercise regimen such as walking 30 minutes a day, five days a week.
The DPP researchers found that participants who adopted these lifestyle changes lost an average of 15 pounds during the first year of the study. Over a 3-year period, they reduced their risk of developing Type 2 diabetes by 58 percent. Adults ages 60 and older saw an even greater benefit: a 71 percent reduced risk.
These lifestyle changes had lasting effects. After 10 years, they were associated with a 34 percent reduced overall risk of developing diabetes and a 49 percent reduced risk among older adults.