It’s well established that older people are at higher risk for developing type 2 diabetes. The reasons why this is the case, though, aren’t totally clear. Many people go through changes in their metabolism as they get older, and some people gain weight as they age — but the higher risk of type 2 diabetes with age doesn’t just apply to people who are overweight or obese.
But many older people undergo changes in body composition that aren’t as simple as just gaining or losing weight. The relative amounts of different tissues in the body may change, with many people losing muscle as they age, and some gaining body fat. These changes may be subtle in some people and not necessarily noticeable from the outside. So in an effort to understand how body composition is related to developing diabetes, researchers measured lean and fat mass in a group of older adults as part of the Baltimore Longitudinal Study of Aging.
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The study’s findings, published in the Journal of the Endocrine Society, were based on 871 men and 984 women with an average age of 59, and included people both with and without diabetes. Overall, a higher percentage of lean body mass was associated with a lower fasting blood glucose level, a lower blood glucose level 2 hours after an oral dose of glucose, and a lower incidence of prediabetes — in both men and women.
But when looking at how certain measurements were tied to actually developing diabetes during the study’s follow-up period (a median of 7 years), a pattern was seen in men but not in women. In the bottom versus the top quartile (fourth) of men based on the measures of percentage total lean body mass, percentage leg lean mass, and lean to fat mass ratio, the researchers saw a higher risk of developing diabetes. This suggests that loss of muscle mass in men may be responsible for at least some of higher diabetes risk associated with getting older.
As noted in a Healio article on the study, the top quartile of men based on total lean body mass had a 54% lower risk of developing type 2 diabetes than the bottom quartile — a very large difference. Those in the second-highest quartile had an even lower risk, 55% lower than the bottom quartile. So being in the top half of men when it came to lean body mass made participants much less likely to develop diabetes.
What’s more, the benefits of having a higher percentage of leg lean mass or a higher lean to fat ratio were even greater. Men in the highest quartile based on leg lean mass were 62% less likely to develop type 2 diabetes than those in the lowest quartile, and those in the highest quartile based on lean to fat ratio were 61% less likely than those in the lowest.
No relationship was seen between muscle strength or quality and diabetes risk in men or women. In both sexes, total lean body mass (the overall mount, not the percentage) was associated with a higher risk of developing diabetes, but this relationship might be explained by the fact that people with more body fat also tend to have higher levels of lean mass to go along with it.
The researchers pointed out that skeletal muscle (muscle next to bone) is the most important area of the body for insulin-mediated uptake of glucose from the blood. If overall muscle loss reduces the surface area of skeletal muscles, this could account for at least part of the higher diabetes risk seen in the study. Future studies that directly measure skeletal muscle could shed more light on this relationship
It’s worth noting that staying physically active — including by doing resistance or strength-building exercises — is a great way to help prevent muscle loss with age. Take a look at this article about finding a fitness program that works for you, or check out some tips on making exercise more fun.
Want to learn more about exercising with diabetes? Read “Add Movement to Your Life,” “Picking the Right Activity to Meet Your Fitness Goals” and “Seven Ways to Have Fun Exercising.”