The hidden dangers of prediabetes

Approximately 98 million Americans — more than one in three — have prediabetes, meaning the average amount of sugar (glucose) in their blood is high but not high enough to be diagnosed as diabetes.

Prediabetes occurs when the body has trouble using glucose for energy because cells become less responsive to insulin produced by the pancreas, a state known as insulin resistance. (Insulin facilitates the transport of glucose out of the blood and into the cells.) The unused glucose builds up in the bloodstream. The difference between diabetes and prediabetes is how high blood sugar levels get.

"If you have prediabetes, you obviously want to stop it from progressing to a diagnosis of diabetes," says Dr. Howard LeWine, assistant professor of medicine at Harvard Medical School and editor in chief of Harvard Men's Health Watch. "But if left alone, prediabetes can be dangerous on its own, as it increases your risk for other serious issues, like cardiovascular disease, chronic kidney disease, and fatty liver disease, even if you never get full diabetes."

The big three

Here is a look at each of these three conditions and how they affect people with prediabetes.

Cardiovascular disease. Research has found that people with prediabetes have a 15% greater risk for cardiovascular disease compared to people who don't have it. That's why it's so important to pay attention to other cardiovascular risk factors, such as smoking, blood pressure, and "bad" LDL cholesterol. "People with prediabetes must quit smoking and strive for lower levels of blood pressure and LDL cholesterol compared to those with normal blood sugar," says Dr. LeWine.

The American Diabetes Association recommends people with prediabetes aim for a blood pressure of less than 140/90 millimeters of mercury (mmHg). However, Dr. LeWine suggests those with prediabetes aim for lower numbers, closer to 120/80 mmHg. "But you and your doctor can decide the best goal for you," he says.

Guidelines suggest people with prediabetes keep LDL levels less than 100 milligrams per deciliter (mg/dL). Dr. LeWine says that the lower the LDL, the better, and recommends that people with prediabetes strive for levels of 70 mg/dL or less.

"By driving down your blood pressure and cholesterol, you are less likely to accumulate fatty plaque in your arteries, offsetting the excess risk of heart disease and stroke related to prediabetes," says Dr. LeWine. He recommends lifestyle changes as your primary approach to manage both blood pressure and cholesterol, adding medication if needed.

Chronic kidney disease. Having prediabetes puts extra strain on the kidneys as they work to filter sugar and other waste products from the blood. Over time, this can damage the kidneys. In fact, studies have found that people with prediabetes are up to twice as likely to develop chronic kidney disease compared to people with normal blood sugar levels, and the risk increases the longer a person has prediabetes.

Fatty liver disease. Prediabetes increases the risk for fatty liver disease — now formally known as metabolic dysfunction–associated steatotic liver disease — in several ways. Elevated glucose levels can cause the body to convert excess glucose into fat, which gets stored in the liver. Insulin resistance can impair the liver's ability to process and break down fats, also leading to fat buildup.

Lifestyle changes

Lifestyle changes like weight loss, exercise, and diet are the best ways to manage blood sugar levels and prevent prediabetes from progressing to full diabetes. (Getting sufficient vitamin D also may help.)

"But making healthy lifestyle choices doesn't just help lower blood sugar levels. It also helps reduce your risk of cardiovascular disease, kidney damage, and fatty liver," says Dr. LeWine. "Even if you need medication to reach your blood pressure and LDL cholesterol goals, you will likely need lower doses if you focus on these three areas."

Weight loss. If you are overweight, losing 5% to 10% of your current body weight can improve blood pressure and cholesterol levels. Weight loss if needed is also a key strategy to both prevent and treat fatty liver disease, according to Dr. LeWine.

Exercise. Federal guidelines suggest that everyone get at least 150 minutes of moderate-intensity aerobic exercise weekly. "Also add two or three hours of resistance exercises per week using free weights, machines, or body weight," says Dr. LeWine. The combination of aerobic exercise and resistance training is linked to better blood sugar control, reduced risk of cardiovascular disease, and a healthier liver.

Diet. Reduce your intake of foods high in simple carbohydrates, such as bread, pasta, rice, potatoes, processed foods, and high-sugar beverages like fruit juice and soda. These carbs are quickly digested and can cause blood sugar levels to quickly rise and fall. Replace them with complex carbs, such as those in whole grains, beans, green peas, and lentils. Also, increase your intake of fiber-rich foods.

"Fiber helps with weight loss by slowing digestion, which helps you feel full and less hungry between meals," says Dr. LeWine. And by slowing the body's absorption of glucose, it smooths out spikes in blood sugar.

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