A low-carb diet is a common and effective nutrition strategy for lowering blood sugar levels and improving management of type 2 diabetes. Low-carbohydrate eating patterns can also improving blood sugar in people with metabolic syndrome, a cluster of risk factors that increases the risk of diabetes and heart disease, among other conditions.
That said, a low-carb diet, especially if you have type 2 diabetes, isn’t as straightforward as simply cutting carbs alone. Here are seven of the most important low-carb diet mistakes to avoid for better blood sugar management and overall health.
How Do Diet and Exercise Affect Type 2 Diabetes?
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1. You Don’t Explore All Your Low-Carb Diet Options
There is no universally agreed upon recommendation for how many carbs to eat on a low-carb diet, says Patti Urbanski, RD, CDCES, a clinical dietitian and diabetes educator at St. Luke’s Hospital in Duluth, Minnesota. People who follow a low-carb diet have a lot of freedom to choose how many carbohydrates they’ll eat in a day.
Most Americans get about 45 percent of their total daily calories from carbs, Urbanski says. So, anything less than 26 percent of your daily calories from carbs can be considered low-carb. For someone on a 2,000-calorie diet, that would mean eating fewer than 130 grams (g) of carbs per day.
Very low carb diets, including the keto diet, run as little as 20 to 50 total g of carbs per day.
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. You Don’t Communicate Regularly With Your Healthcare Team
Your diabetes care team can help you determine the right low-carb approach for you. It’s also important to notify them of any diet or lifestyle changes to avoid any potential side effects.
In fact, they may recommend lowering or changing your medications to avoid very low blood sugar levels (hypoglycemia), cardiovascular complications, and diabetic ketoacidosis (DKA), which is a health emergency. This is especially true if you’re taking insulin, insulin-promoting drugs, or blood pressure medications, Urbanski says. Additionally, SGLT2 inhibitors, oral medications that assist the kidneys in lowering blood sugar levels, may push some people into potentially fatal DKA. Eating a low-carb diet can further exacerbate that risk.
“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,” Urbanski says. Examples of SGLT2 inhibitors include canagliflozin (Invokana), dapagliflozin (Farxiga), and empagliflozin (Jardiance).
But working with your healthcare team shouldn’t be limited to simply seeking clearance before starting a new diet. Ideally, they’ll be able to offer ongoing nutritional advice and support. Medicare, for example, covers 10 hours of diabetes self-management training and three hours of medical nutrition therapy initially, then two hours of each service every year for people with type 2 diabetes, Urbanski says.
Some people need annual appointments, while others can benefit from seeing a registered dietitian or diabetes educator every two to three months.
While a low-carb diet can help stabilize your blood sugar, it’s still important to monitor it carefully to prevent periods of hyperglycemia or hypoglycemia, says Vandana Sheth, 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, use a continuous glucose monitor (CGM), which takes a blood sugar measurement every 5 minutes or less. Medicare covers CGMs for people who use insulin. Your private insurance may, too, and there are over-the-counter devices for people who can afford to pay on their own.
4. You Focus Too Much on Total Carbs and Not Enough on Carb Quality
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.
When following a low-carb diet, the more you can focus on whole, unprocessed foods, the better. These foods can include healthy 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 keto diet or trying to build lean muscle through an increase in dietary protein, Urbanski says.
If you become too focused on reducing carbs, you may end up replacing them with high-calorie fats, as well as sugar-free foods that contain artificial sweeteners, which may encourage you to eat more.
5. You Get All Your Carbs at Once Rather Than Spreading Them Out
If you eat too few carbs at each meal, you may have difficulty sustaining this diet long-term, Urbanski says. You may end up reaching for high-carb snacks during the day, which can cause large dips and spikes in your blood sugar levels.
Evenly distributing carb intake throughout the day can prevent these dips and stabilize your levels.
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 and snacks you plan to eat throughout the day.
6. You Miss Out on Fiber, Which Is a Powerhouse Nutrient
Fiber is critical to overall health: It lowers blood pressure, improves insulin health, and encourages weight loss by stabilizing blood sugar and increasing satiety, Zanini says.
But Americans aren’t getting enough fiber, even when eating carb-rich diets. On average, male adults with type 2 diabetes typically consume 4.2 percent of the recommended amount of fiber, while female adults with the condition consume 8.1 percent.
The recommended daily amount of fiber for adults up to age 50 is 25 g for women and 38 g for men. Women and men older than 50 should have 21 and 30 g daily, respectively.
When following a low-carb diet, try to add plenty of high-fiber foods to your meals. Low- to moderate-carb options include leafy greens, berries, legumes, and low-carb, high-fiber breads and tortillas, Sheth says.
If you have trouble meeting your protein needs or you experience constipation, which is a sign that your digestive system may need more fiber, you can try taking fiber supplements. But don’t use them in place of regularly eating high-fiber plant foods, Sheth says. These supplements don’t contain the array of vitamins and minerals that fruits and vegetables also contain.
7. You Drink Too Little Water, Increasing Your Risk of Dehydration
Following a low-carb, high-protein diet, such as the keto diet, can increase the risk of dehydration, as well as electrolyte imbalances, Urbanski says. This happens because when the body stores carbohydrates, it stores water along with it. 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.Proper hydration helps support steadier blood sugar levels.
If you’re aiming to eat less food as part of your low-carb plan, this can lower your sodium levels even more. Dehydration and too-low sodium levels can cause lightheadedness and dizziness, and prevent your cells from functioning optimally, she says. These dehydration symptoms are a part of the so-called keto flu that often afflicts new low-carb dieters.
Be sure to speak with your healthcare team about how much salt you should be consuming to prevent dehydration and heart issues. In people with high blood pressure or congestive heart failure, for example, increasing sodium intake may not be a healthy option, she says. As for water intake, check out the Everyday Health Hydration Calculator.
The Takeaway
Consuming a low-carb diet can help people with type 2 diabetes effectively manage their blood sugar levels.
When starting out, it’s important to avoid some common low-carb diet mistakes, such as not focusing on carb quality and not drinking enough fluids, so that your diet can work most effectively to protect your health.
Work with your healthcare team to determine which type of low-carb diet may be right for you. Too few carbs can make it tougher to stick to your diet, while dehydration can lead to uncomfortable symptoms, such as dizziness and fatigue.
While a low-carb diet is generally beneficial for managing blood sugar levels, it’s still important to monitor your blood sugar levels. If you detect very high or low blood sugar levels, you may need to adjust your portion sizes or medication.
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
Thomsen MD et al. The Clinical Effects of a Carbohydrate-Reduced High-Protein Diet on Glycaemic Variability in Metformin-Treated Patients with Type 2 Diabetes Mellitus: A Randomised Controlled Study. Clinical Nutrition Espen. October 2020.
Oh R et al. Low-Carbohydrate Diet. StatPearls. August 17, 2023.
Guirguis H et al. The Use of SGLT-2 Inhibitors Coupled With a Strict Low-Carbohydrate Diet: A Set-Up for Inducing Severe Diabetic Ketoacidosis. Clinical Medicine Insights: Case Reports. April 8, 2022.
Miketinas DC et al. Usual Dietary Fibre Intake According to Diabetes Status in USA Adults — NHANES 2013-2018. British Journal of Nutrition. September 28, 2023.
Dietary Fiber: Essential for a Healthy Diet. Mayo Clinic. December 11, 2024.
Skartun O et al. Symptoms During Initiation of a Ketogenic Diet: A Scoping Review of Occurrence Rates, Mechanisms and Relief Strategies. Frontiers in Nutrition. March 25, 2025.
Julie Cunningham has been a registered dietitian for more than 25 years. She is a certified diabetes care and education specialist (CDCES) and an international board-certified lactation consultant. She has served as the president of the Foothills Chapter of the North Carolina Dietetics Association (NCDA) and has been a member of the executive board of the NCDA.
Ms. Cunningham received a bachelor's degree from Appalachian State University in North Carolina. She subsequently completed a master's degree in public health nutrition at the University of North Carolina at Chapel Hill.
Ms. Cunningham has worked in women's and children's health, cardiology, and diabetes. She is the author of 30 Days to Tame Type 2 Diabetes, and she has also written for Abbott Nutrition News, Edgepark Medical Health Insights, diaTribe, Babylist, and others.
A resident of beautiful western North Carolina, Cunningham is an avid reader who enjoys yoga, travel, and all things chocolate.
K. Aleisha Fetters is a Chicago-based fitness writer and certified strength and conditioning specialist who empowers others to reach their goals using a science-based approach to fitness, nutrition and health. Her work has been featured in various publications including Time, Men's Health, Women’s Health, Runner’s World, Self, O, U.S. News & World Report, and Family Circle. She also creates editorial content and programming for Exos, a sports performance company.
Fetters earned both her bachelor’s and master’s degrees in journalism from the Medill School of Journalism at Northwestern University. She has written multiple books -- Give Yourself MORE, Fitness Hacks for Over 50, My Pocket Guide to Stretching -- and coauthored The Woman’s Guide To Strength Training. She is regularly interviewed as an expert on strength training, women's fitness, and mindset. She works with trainees in person and online.
