Muscle and Blood Sugar: Why Lean Mass Matters

When people think about blood sugar, they think about food and medication. Muscle rarely comes up. It should, because muscle is the largest place the sugar from a meal can go.

Where glucose goes

After you eat carbohydrate, glucose enters the blood and insulin rises. Insulin signals tissues to pull that glucose in. Studies that measure this directly show that skeletal muscle accounts for roughly 70 to 80% of the glucose cleared from the blood under insulin stimulation. The rest goes mainly to the liver, the brain and other tissues.

Muscle stores that glucose as glycogen. Think of each muscle as a storage tank. The more muscle you carry, the more total tank space you have. When the tanks are small or already full, glucose has fewer places to go, it stays in the blood longer, and the pancreas has to release more insulin to push it in. Over years, needing more and more insulin to do the same job is insulin resistance, the path to prediabetes and type 2 diabetes.

Exercise opens a second door

Muscle can also take up glucose without much insulin at all. When a muscle contracts, it moves glucose transporters to its surface on its own. That is why a walk after a meal lowers the glucose rise, and why regular training improves insulin sensitivity for a day or more afterward. Training also empties the glycogen tanks, making room for the next meal.

Low muscle, high fat

Two things on a body composition scan predict trouble with blood sugar. One is low muscle. The other is too much fat, especially visceral fat around the organs, which interferes with insulin signaling in the liver and muscle. The worst combination is both together, and it often looks unremarkable from the outside. A person can have a normal weight and a normal BMI while carrying low muscle and high visceral fat.

That combination becomes more common with age. Adults lose roughly 3 to 8% of muscle per decade after about 40 without resistance training, and fat tends to take its place while the scale barely moves.

What we measure

A DEXA scan shows both sides of the problem. It measures lean mass by region, which we use to calculate ALMI, the lean mass in your arms and legs divided by height squared, compared with age and sex percentiles. It also measures total body fat percentage and estimates visceral fat. Paired with labs such as fasting insulin and A1c, it gives a clear picture of where the risk is coming from.

Strength training and protein are the two main levers for building and keeping muscle. A repeat DEXA about every 6 months shows whether lean mass is going up and visceral fat is coming down.

Blood sugar is not only about what you eat. It is also about where the sugar can go. That is why we check it. You can pick your time right after you buy.

Book a DEXA scan at HYBRD Health ($199)

This article is educational and is not medical advice.