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You might keep tabs on your cholesterol and blood pressure, but what about your blood sugar levels? About 20 percent of the 37 million U.S. adults with diabetes and more than 80 percent of the 96 million with prediabetes don’t know they have those conditions.
That’s especially concerning, because diabetes and prediabetes also mean a higher risk for heart disease; vision, kidney, and nerve damage; and even some cancers.
Food is a powerful tool for keeping blood sugar, or glucose, levels in check. And making healthy choices can help you avoid prediabetes or reduce your chances for progressing from prediabetes to Type 2 diabetes, and manage your glucose levels if you already have the disease, says Hope Warshaw, a certified diabetes care and education specialist in Asheville, N.C.
A healthy diet may be especially helpful for older adults. In the landmark Diabetes Prevention Program (DPP) study, older participants with prediabetes who ate healthier, exercised regularly and lost a little weight cut their risk of progressing to Type 2 diabetes by 71 percent during the 2.8-year study period.
The goal of following a diabetes or prediabetes diet is to prevent insulin resistance. Usually after eating, blood glucose rises and the pancreas releases insulin. Insulin shuttles glucose into the cells, where it’s used for energy. Insulin resistance occurs when the pancreas can’t keep up with the demand for insulin. Eventually, you make less of it, and glucose levels stay higher than they should. For people with prediabetes and Type 2 diabetes, a diet that increases the body’s sensitivity to the insulin they continue to make is critical, Warshaw says. And for others, it may help keep the conditions at bay.
But many of us don’t know what to sip, munch and crunch. Here, we clear up a few of the most common misunderstandings about diet and blood glucose control and offer steps that can make a difference.
Which carbs to eat for glucose control, and how much of them, can be confusing. “ ‘Bread is the enemy’ is something I’ve heard throughout my career,” says Lisa Jones, a registered dietitian in Philadelphia who counsels clients with diabetes and prediabetes. “And people newly diagnosed with diabetes say ‘I can’t have fruit because it has sugar.’ ”
But not all carbs are the same. Research shows that some, like refined flour, potatoes and foods with a lot of added sugars, can rapidly raise blood sugar and increase diabetes risk. For example, in a 2019 study published in Diabetes Care, people who cut out one sugary drink per day lowered the risk by 10 percent.
On the other hand, carb-containing whole foods like fruit, beans and whole grains have fiber and can slow the rise in blood glucose after meals. Levels don’t spike and the pancreas isn’t taxed.
Studies support their benefits. For example, a daily serving of whole grains cut diabetes risk by 7 to 11 percent in a Danish study of 55,465 older adults. And in a 2021 Australian study, middle-aged and older adults who ate about two servings of fruit per day were 36 percent less likely to develop diabetes over five years compared with those who skimped on fruit.
Another bonus: Whole grains, beans, fruits and vegetables supply flavonoids and other polyphenols, compounds that help with insulin sensitivity, too.
Extra pounds raise your risk for diabetes by sending more fat into muscle cells, which makes it difficult for your muscles to absorb blood sugar. But “people with diabetes or prediabetes can get overwhelmed by numbers and think they have to lose a lot of weight,” Jones says. “Really, just small amounts make a big difference.” Dropping only 5 to 7 percent of your body weight (10 to 14 pounds if you now weigh 200 pounds) cut the risk for diabetes in the DPP study. Still, “I don’t care that someone loses 25 pounds,” Warshaw says. “It’s better to lose 5, 10 or 15 pounds relative to your size and keep as many pounds off as possible. Gaining back the weight will likely increase insulin resistance again.”
Picking unsaturated fats like vegetable oils, nuts, avocado and fish over foods packed with saturated fat like butter and red meat could lower blood glucose enough to cut diabetes risk by 22 percent, a 2016 study found. “Fats aren’t just carriers of calories, they’re the most important structural molecules in the body,” says Dariush Mozaffarian, dean of the Friedman School of Nutrition Science and Policy at Tufts University. In particular, polyunsaturated fats (found in safflower and sunflower oils) may support insulin production and help muscles respond to insulin’s commands to absorb blood sugar. In contrast, saturated fats seem to increase insulin resistance by packing extra fat into your liver.
Sixty-two percent of those 65 and older in the United States with diabetes take supplements, according to a 2020 study in BMJ Open Diabetes Research & Care. These include cinnamon, bitter melon, fenugreek and magnesium. Manufacturers may claim that they “support” healthy blood sugar or that they’re “natural diabetes cures,” but there’s little scientific evidence that they work, the National Institutes of Health says. “My approach is food first,” Jones says. So try cinnamon on whole-wheat toast, in fruit salad or in coffee. And before taking supplements, talk to your doctor.
While products made to manage blood sugar may help, they’re highly processed foods, containing protein extracts or isolates, many additives and sugar substitutes, for instance. A 2022 study of more than 70,000 people found that those who ate the most ultraprocessed foods had an 80 percent increased risk for developing Type 2 diabetes compared with those who ate the least. And other studies have had similar findings.
You can lower your glucose levels by snacking on whole foods, which have the added benefit of being packed with nutrients. Try a shake made with yogurt, fruit, some avocado for creaminess and a handful of spinach or kale to bump up fiber and nutrient levels. “You won’t even notice the greens; they disappear,” Jones says. A handful of nuts, some yogurt, and berries, or carrots dipped in peanut butter are also good options.
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