7 Low-Carb Diet Mistakes to Avoid When You Have Diabetes

Carbohydrates increase blood sugar levels: This you know. So it’s only natural that cutting carbs and turning to low-carb diets is a common nutrition strategy for lowering blood glucose levels and improving management of type 2 diabetes.

For example, one study found that a low-carb, high-protein diet is an effective strategy to minimize blood sugar spikes in people with type 2 diabetes. And in a separate review of research from 2021, a low-carb diet was shown to help people with metabolic syndrome — a cluster of conditions including abdominal obesity and high cholesterol, triglyceride, blood pressure, and fasting blood sugar levels — improve their numbers, even when they don’t lose weight.

RELATED: 5 Ways to Lower Your A1C

That said, following a low-carb diet, especially if you have type 2 diabetes, isn’t as straightforward as simply cutting carbs. Here are seven of the most common, most important low-carb diet mistakes to avoid for better blood sugar management and overall health.

1. Not Exploring All of Your Low-Carb Diet Options

What “low-carb” actually constitutes varies from person to person and researcher to researcher. No universally agreed upon recommendation exists for how many carbs you should eat on a low-carb diet, explains Patti Urbanski, RD, CDCES, a clinical dietitian and diabetes educator at St. Luke’s Hospital in Duluth, Minnesota.

That said, in broad strokes, getting less than 26 percent of your daily calories from carbs can be considered low-carb, according to one article. For someone eating a 2,000-calorie diet, that would mean eating fewer than 130 grams (g) of carbs per day.

“Very low-carb” diets involve eating as little as 20 to 50 total g of carbs per day. Ketogenic diets, which have some overlap with very low-carb diets, can often require eating even fewer carbohydrates per day. (Most Americans get about 45 percent of their total daily calories from carbs, Urbanski says.)

RELATED: How Do You Tell the Difference Between Good and Bad Carbs?

Which approach is right for you? “There are many factors that must be considered when deciding how many carbs an individual should consume daily,” says Lori Zanini, RD, CDCES, a registered dietitian in private practice who’s based in Manhattan Beach, California. “Some of these factors include how well-controlled blood sugar levels are, current medications or insulin, additional health conditions, food preferences, budget, and health goals.”

2. Not Regularly Communicating With Your Healthcare Team

Your diabetes care team can help you determine the right low-carb approach for you, but it can also help to avoid any bad, potentially dangerous, or life-threatening side effects of going low-carb to help manage type 2 diabetes.

You and your doctor may need to lower or change your meds to avoid low blood sugar, or hypoglycemia; cardiovascular complications; and diabetic ketoacidosis (DKA), which is a health emergency. This is especially true for people taking insulin, insulin-promoting drugs, or blood pressure medications, Urbanski says. Additionally, SGLT2 inhibitors, oral medications that assist the kidneys in lowering blood glucose levels, push some people into potentially fatal DKA, with low-carb intake further exacerbating that risk, she says. “It’s recommended that someone on SGLT2 inhibitors should not go on a low-carb diet or should first discontinue and change medications under their doctor’s supervision,” she says. According to the U.S. Food and Drug Administration, examples of SGLT2 inhibitors include canagliflozin (Invokana), dapagliflozin (Farxiga), and empagliflozin (Jardiance).

For the best results, though, working with your healthcare team shouldn’t be limited to simply seeking clearance before starting a new diet. As Urbanski explains, Medicare covers two hours of diabetes education and two hours of nutritional services every year for people with type 2 diabetes. “Medicare tends to only pay for things that are thoroughly proven to work,” she says, so getting at least those four hours per year is a good goal. She adds that some people need only annual appointments, while others can benefit from seeing a registered dietitian or diabetes educator every two to three months.

To find a registered dietitian nutritionist, log on to the Academy of Nutrition and Dietetics’ national referral service. You can also look for certified diabetes care and education specialists through the Certification Board for Diabetes Care and Education.

RELATED: What Are the Pros and Cons of SGLT2 Inhibitors?

3. Not Staying on Top of Monitoring Your Blood Sugar

Following a low-carb diet can help stabilize blood sugar levels, but following a low-carb diet doesn’t guarantee they’re stable. Without careful monitoring, periods of both hyperglycemia and hypoglycemia can occur, explains Vandana Sheth, RDN, CDCES, a Los Angeles-based registered dietitian nutritionist.

“When you go on a low-carb diet, monitoring your blood sugar can provide important information that you can use to adjust meal portions as well as medication dosages,” she says. To get the most complete info and make the most informed decisions, try continuous glucose monitor (CGM), which takes a blood sugar measurement every five minutes or less. Medicare covers CGM for people who use insulin, and so may your private insurance.

4. Focusing Too Much on Total Carbs and Not Enough on Carb Quality

For the best health, following a low-carb diet shouldn’t just be about what you cut. It should also be about what you add into your nutrition plan, Zanini says. After all, a healthy diet meets all of your body’s nutritional needs and doesn’t exceed your body’s caloric needs.

But when people become narrowly fixed on reducing carbs, they can easily wind up replacing those carbs with high-calorie fats, as well as chemical-laden sugar-free foods and artificial sweeteners. When following a low-carb diet, the more you can focus on whole, unprocessed foods, the better. These foods can certainly include high-fat foods, such as olive oil, avocado, walnuts, and salmon, but the exact amount of fat you should eat depends on whether you are following a ketogenic diet or trying to build lean muscle through an increase in dietary protein, Urbanski says. Again, keeping an open dialogue with a registered dietitian is helpful.

Still, you don’t have to work directly with a registered dietitian to take advantage of their knowledge. The Academy of Nutrition and Dietetics’ EatRight.org website is a great resource for expert nutritional information, eating strategies, and healthy recipes.

RELATED: 12 Low-Carb Diets and Their Pros and Cons

5. Getting All of Your Carbs at Once Rather Than Spreading Them Out

The lower you make your carb intake goal, the more difficult sustaining the diet 24/7 can become, Urbanski says. In some cases, you may be tempted to “save” your carbs for dedicated high-carb treat meals or snacks, but resist the urge. Evenly distributing carb intake throughout the day is critical for preventing large dips and spikes in blood sugar, as well as keeping energy levels up and the brain working at top speed. Sheth recommends that most people with type 2 diabetes aim to consume 30 to 45 g of carbs per meal. To figure out the right balance for you, divide your goal number of daily carbohydrates by the number of meals you plan to eat throughout the day. Snacks also count toward this total but should generally be lower in carbs compared with meals.

6. Missing Out on Fiber, Which Is a Powerhouse Nutrient

Fiber is critical to overall health, lowering blood pressure, improving insulin health, and encouraging weight loss by stabilizing blood sugar levels and increasing satiety levels, Zanini says.

Problem is, most Americans aren’t getting enough fiber — even when eating carb-rich diets. According to a study from January 2023, on average, people with type 2 diabetes consume 12 to 13 percent of the daily recommended amount of fiber. The USDA’s recommended daily amount for adults up to age 50 is 25 g for women and 38 g for men. Women and men older than age 50 should have 21 and 30 g daily, respectively.

When following a low-carb diet, make a point to integrate plenty of high-fiber foods into your meals. Low- to moderate-carb options include leafy greens, berries, legumes, chia seeds, and low-carb, high-fiber breads and tortillas, Sheth says. If you still have trouble meeting your protein needs or you start to experience constipation — a sign that your digestive system needs more fiber — you can try adding in fiber supplements. The key is using them as supplements; don’t use them as a crutch to get out of eating high-fiber plants, Sheth says. While fiber supplements certainly deliver on fiber, they don’t contain the array of vitamins and minerals that fruits and vegetables also contain.

RELATED: Why Is Fiber Important for Your Digestive Health?

7. Drinking Too Little Water, Leaving Yourself at Risk for Dehydration

Left unchecked, going low-carb can increase the risk of dehydration, as well as electrolyte imbalances, Urbanski explains. This happens because when the body stores carbohydrates, it stores water along with it. Furthermore, in response to reduced blood sugar levels, the body doesn’t produce as much insulin. In turn, the kidneys expel both water and sodium from the body, she says.

Also, if your low-carb plan involves removing a lot of sodium-laden foods like potato chips from your diet (which is a good thing), it can also lower sodium levels.

Both dehydration and too-low sodium levels can bring on lightheadedness and dizziness, as well as keep the cells throughout the entire body from optimally functioning, she says. Keep open lines of communication with your healthcare team before loading up on salty foods, however. In people with uncontrolled high blood pressure or congestive heart failure, for example, increasing sodium intake may not be a healthy option, she says. As for water intake, EatRight.org recommends 15½ cups of fluid per day for men and about 11½ cups per day for women, but ask your healthcare team about the optimal amount of fluid for your individual health.