Is your A1C high? Here’s what to do and what to eat and not eat

There is no one cause of prediabetes, but family history of diabetes, age, diet, lifestyle, being overweight, and insulin resistance can play a role. As a borderline condition — higher than normal blood sugar, but not to the level of diabetes — prediabetes can be reversed or improved by eating more healthfully, exercising more, and losing weight. If ignored, it can advance to type 2 diabetes, where elevated blood sugar can damage blood vessels, the heart, nerves, kidneys, liver, eyes, and more.

“I see a lot of people with prediabetes,” says Marc O’Meara, senior nutritionist at Brigham and Women’s Hospital. He explains that too many Americans eat a diet high in processed foods, carbs, and sugar. “As we age, we don’t burn sugars as well,” he says. (I think he was talking to me.)

In a nutshell, when you eat or drink carbohydrates, the digestive system breaks down the carbs into sugar (glucose), which is carried through the bloodstream and into cells as the body’s main source of fuel. Our pancreas produces the hormone insulin, which helps glucose get into our cells. When you have prediabetes, too much sugar remains in the blood.

To reduce blood sugar levels, the key is consuming fewer carbs, especially refined carbs (those with minimal or no nutrients), and pairing carbs with protein, healthy fats, and vegetables. What you eat and the order in which you eat will affect how fast or slow sugars are absorbed into the bloodstream. It’s helpful to work with a health care professional at this stage to learn about diet and lifestyle choices and blood glucose monitoring.

O’Meara uses a “dam” analogy to describe the beneficial interaction between protein and carbs. If you eat, say, balanced portions of chicken and rice, the chicken (protein) sets up a dam in your digestive system that slows the flow of sugars (from the rice carbs) into the blood. If you eat just rice or other carbs without protein (the dam), sugars flood the bloodstream and spike your blood sugar. Also, eating protein and non-starchy vegetables before carbs helps us feel full, says O’Meara.

The best eating plan for someone with prediabetes is essentially the Mediterranean diet, says O’Meara. It emphasizes lean protein (with low saturated fat), seafood, low-fat dairy, beans and lentils, plenty of vegetables, and moderate amounts of whole grains and fruit.

The American Diabetes Association’s Diabetes Plate is a good way to create — and visualize — healthful low-carb meals. The ADA recommends filling a 9-inch dinner plate as follows:

• Half of the plate filled with non-starchy vegetables, such as leafy greens (kale, spinach, chard, collards), broccoli, cauliflower, Brussels sprouts, cucumbers, zucchini, and peppers. Non-starchy vegetables are low in carbs and calories and high in nutrients and fiber.
• A quarter of the plate with lean protein, such as chicken, turkey, and other lean meats; plant-based protein, such as beans, lentils, tofu, nuts and seeds; seafood; eggs; and low-fat dairy and cheese. (Note: Beans and lentils are technically carbs, but they’re a great source of protein and fiber. Dairy products contain lactose, a natural sugar, but also provide protein and calcium. Healthy fats in nuts, seeds, avocado, and olive oil contain important nutrients and increase satiety.)
• A quarter of the plate with carbohydrates, such as starchy vegetables (corn, sweet potatoes, winter squash, peas, potatoes); whole grains (quinoa, brown rice, farro, buckwheat, bulgur); whole wheat bread and pasta; legumes; and fruits.

The best carbs are complex carbs, rich in nutrients and fiber, which take longer to digest than refined carbs. The latter, including white bread, white pasta, white rice, sugary cereals, and sweetened beverages, causes quicker and greater blood sugar spikes.

Because carbs have the biggest impact on blood glucose, portion sizes are important. A serving of carbs is about 15 grams, equal to one slice of whole wheat bread, ⅓ to ½ cup whole grains, one small piece of fruit, or ¾ cup of berries, and ½ cup starchy vegetables or beans. Be aware that on product packages, like your favorite pasta, serving sizes are often equivalent to 30-plus grams of carbs. O’Meara suggests using your hand as a guide: “It’s a palm of protein, a palm of carbs, and two palms of non-starchy vegetables.” You can calculate net carbs for a particular food, which is total carbs minus fiber. “That’s the amount of sugars heading down the river,” he says. (Net carbs is only relevant if the food contains high fiber.)

Exercise is also important for lowering blood sugar levels. “The combination of eating well and exercise gives you the biggest bang for your buck,” says Teresa Fung, adjunct professor of nutrition at the Harvard T.H. Chan School of Public Health. “Physical activity draws glucose from the blood and into cells and the muscles themselves to use for fuel,” she says. “The greater the intensity and duration, the more effective the activity will be at lowering blood glucose.”

For people with prediabetes, eating right is very much about planning meals thoughtfully. It starts with breakfast. “My cereal eaters struggle the most,” says O’Meara. If opting for cereal, choose a healthful whole grain, low-sugar variety. “Get protein in there with nuts and seeds or eat an egg first, then have a small bowl of cereal,” he says. “If you eat carbs first, it will spike your blood sugar. If you eat carbs last, you’ll have less of a spike and better results.” As he reminds his clients: “Set up the dam.”

For me, then, gone were my homemade (healthful!) morning muffin with coffee, at least not until after I ate some yogurt, cottage cheese, or eggs. I ate one slice of whole-grain toast, not two. I still had an occasional bowl of cereal (my favorite whole grain flakes or homemade granola), but a smaller portion.

Fruit lovers have some adapting to do. Although fruit contains vitamins and fiber, it’s high in natural sugar. I learned to eat half an apple (sad!) as a snack, often with a chunk of cheese or smear of peanut butter. My favorite evening dessert of frozen mango chunks and Bing cherries is now a slightly smaller bowl with a dollop of Greek yogurt on top. “You can replace starches like pasta and grains with a portion of fruit; they both turn into sugar,” says O’Meara. In other words, he says, “Choose a carb!”

But who wants only half an apple or meatballs without spaghetti? O’Meara says everyone’s glucose response is different, so I should “test the apple.”

That’s where the powerful tool of continuous glucose monitors comes in. CGMs are coin-size devices, generally worn on your upper arm, with a tiny needle sensor placed under the skin that measures glucose in the interstitial fluid between cells. Most disposable devices last two weeks, and their data is accessible in real time via an app downloaded onto your phone. “People with prediabetes can make use of the data and patterns to learn how the body responds to carbs,” says Fung.

I wore a CGM for two weeks and learned how my blood glucose responded to what I ate and my activity level. I exercised a little more and snacked a little less. I was sometimes hungry and, yes, often sad that I had to give up or reduce portions of my favorite foods. Fortunately, I’ve always loved vegetables and salads, so eating more of these was easy. My largest glucose spike was after a dish of Thai pad see ew, which was long on saucy rice noodles and short on chicken and veggies. My second-highest reading was after a burger on half a bun and 12 French fries.

There are various CGM brands to choose from, sold with or without a prescription. Many brands offer a subscription plan for more frequent use. Insurance coverage varies; Medicare will only cover CGMs if you have diabetes, but not prediabetes. (So much for preventative medicine.)

The million-dollar question everyone with prediabetes asks is how many grams of carbs they should eat in a day. According to the ADA, the recommended minimum for carbs is 130 grams per day to meet the body’s energy needs. “There is no magic number,” says Fung, adding that it depends on your body size, age, health conditions, activity level, and goals. The recommended A1C test (and other monitoring, as needed) will reflect whether you’re in the healthy range for blood glucose — an A1C below 5.7 percent is normal — and, therefore, if your carb consumption is appropriate.

I stuck with my new eating plan because the motivation to keep diabetes at bay was and continues to be very strong. I took a second A1C test recently and was thrilled to see my efforts pay off with a drop in my A1C from 6 percent to 5.5 percent, just into the normal blood sugar range. I know the modifications can’t be a one-and-done, but they are a can-be-done. This needs to be my (mostly) new normal. I plan to wear a CGM again soon to test that whole apple. I have some homemade German chocolate cake in the freezer, and I’ll test my glucose response to that too. (A small piece!) Like Goldilocks, I’ll see if there’s a difference between a baby bowl of my granola and a mom-size portion.

Just as there is no one cause of prediabetes, there is no one best diet and/or lifestyle to reverse or manage it. But eating more healthfully to lower blood sugar levels is key. “Long-term, it’s continuous high blood glucose that is the problem,” says Fung. “Occasional spikes are not going to make a big difference. Next day, do better.”

Lisa Zwirn can be reached at [email protected]

Lisa Zwirn can be reached at [email protected].