Food is a big deal for people with diabetes. Just about everything we eat has an impact on our blood glucose levels, and a healthy diet is key to good cardiovascular and metabolic health. What we eat is one of the most important factors — along with physical activity and the proper use of medication — in diabetes management. So, what should people with diabetes eat?

Is there a perfect diabetes diet?

In a word, no. There is no single officially recommended diet or eating pattern for diabetes. Medical authorities now recognize that there are many different ways of eating that can help people manage diabetes, including type 1 diabetes, type 2 diabetes, gestational diabetes, and prediabetes.

Low-carb, low-fat, Mediterranean, vegan: Experts agree that all of these diets (and more) have their plusses and minuses, and that all can be healthy choices.

The American Diabetes Association regularly publishes its interpretation of mainstream expert thinking on nutritional therapy for diabetes. The most recent update, which informs most of what we write below, was released in 2019. The ADA has a high standard of evidence — the organization only considers randomized controlled trials of a certain size and length — which helps avoid all the anecdotes and pseudoscience that cling to this topic on the internet.

This article will review the highest-quality scientific evidence both in favor of the most popular eating patterns for people with diabetes.

The Three Things (Almost) Every Healthy Diabetes Diet Has in Common

Before we get to individual diets, it’s helpful to start with some general guidelines. The ADA highlights these three key factors that almost every recommended diabetes diet shares:

1. Eat more nonstarchy vegetables. Think broccoli, kale, salad greens, mushrooms, peppers, peas, etc. These veggies typically pack in a ton of nutrition with very few carbs and calories.
2. Eat less sugar and refined grains. Sugar, of course, leads to dramatic blood glucose spikes, but it’s also probably best to minimize staple starches like flour, pasta, bread, and white rice. These simple carbs can provoke big blood sugar increases, too.
3. Choose whole foods over highly-processed foods. Whole foods usually have more protein and fiber, they’re lower-calorie, and they have many other health benefits. The more processed a food is — think junk food and boxed dinners — the more likely it is to be loaded with sugar, salt, and fat. These foods are basically engineered to make you overeat.

These three guidelines should work for the vast majority of people with diabetes and prediabetes. No matter what dieting framework you choose, routinely making the choices outlined above will almost certainly help lead to better glycemic control and better overall health.

There may be some exceptions. Some people — for example, those who have undergone bariatric surgery, or those living with advanced kidney disease — may be unable to follow all three precepts. And a very small number of health-conscious eaters, such as the proponents of the all-meat “carnivore” diet, have chosen to ignore one or more of these guidelines.

There is No Ideal Macronutrient Mix

Carbohydrates, protein, and fat are the macronutrients that make up the human diet. Many diets and eating patterns work by outlining exactly how much of each macronutrient you’re allowed to eat.

Many of us have been instructed by our doctors or other medical professionals to stick to the USDA Dietary Guidelines for Americans (PDF). This document, which is issued every five years, gives Americans very precise “goals” for macronutrient intake. For example, women aged 31-50 are told to target 130 grams of carbohydrates daily, constituting 45-65 percent of their total caloric intake.

The ADA has politely rejected this advice:

Although numerous studies have attempted to identify the optimal mix of macronutrients for the eating plans of people with diabetes, a systematic review found that there is no ideal mix that applies broadly and that macronutrient proportions should be individualized.

There is no ideal macronutrient mix. Your carb, protein, and fat targets are up to you, ideally with input from a doctor, and should be based on an “individualized assessment of current eating patterns, preferences, and metabolic goals.”

Carbs and Glycemic Control

People with diabetes — especially those of us that use insulin — know that carbohydrates are the most troublesome part of our diets. That’s because carbs, more than anything else we eat, prompt the blood sugar increases that define diabetes and largely cause its dangerous long-term complications.

To put it simply, if you have diabetes, it makes a whole lot of sense to eat fewer carbs. It’s possible that you’ve heard conflicting advice on this matter. Here’s what the ADA says today:

Reducing overall carbohydrate intake for individuals with diabetes has demonstrated the most evidence for improving glycemia and may be applied in a variety of eating patterns that meet individual needs and preferences.

It’s official: Eating fewer carbs is the best way to improve your blood sugar.

The ADA also confirms that we do not truly need carbohydrates. It’s common to hear that an adult needs at least 130 grams of carbs per day, as per the USDA recommendations, but the ADA notes that “this energy requirement can be fulfilled by the body’s metabolic processes … in the setting of very low dietary carbohydrate intake.”

This advice doesn’t necessarily mean that everyone should be on a low-carb or ketogenic diet. But it does mean that carbohydrate restriction is a great option for anyone struggling with high blood sugar. In fact, carb restriction is so effective that it usually comes with a warning for people with diabetes: if you reduce your carb intake, you may need to be ready to reduce your use of insulin and other glucose-lowering medications to avoid a risk of hypoglycemia.

Carbohydrate restriction can be incorporated into almost any other diet, including vegan, vegetarian, and Mediterranean eating patterns.

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Alternative Eating Patterns

It’s clear that the “standard American diet,” with its heavy reliance on sugar, simple starches, and highly-processed foods, is no good for people with diabetes. While it’s possible to eat a healthy diabetes diet without choosing a particular eating pattern, many people find it helpful to use the framework of a diet. The ADA has evaluated the science of a number of alternative eating patterns:

Mediterranean Eating Patterns

The Mediterranean diet is an eating pattern based on foods and traditions found in European countries near the Mediterranean Sea. Think Greece, Italy, and Spain, countries celebrated for their sunny cuisine, and especially for the copious use of olive oil, fresh seafood, legumes, herbs, wine, fresh fruits, and vegetables. Red meat and animal fats should be somewhat limited.

The ADA reports that the Mediterranean diet has only a “mixed effect” on A1C, weight, and cholesterol levels, but that it may reduce the risk of cardiovascular disease. For those with prediabetes, Mediterranean diets may reduce the incidence of type 2 diabetes in the first place.

Vegetarian / Vegan Eating Patterns

Every year, more and more people opt to eat plant-forward.

Avegetarian diet eliminates meat products, but allows eggs and/or dairy products. A vegan diet eliminates all animal products — no eggs, no dairy, and usually no honey either. There are several more specific variations of each, depending on exactly what ingredients are permitted.

Many studies have found that people eating vegetarian and vegan diets are healthier than those eating conventional diets. Various plant-forward diets have been associated with a lower risk of cancer, lower blood pressure, and less chronic disease.

The ADA determined that high-quality studies of people with diabetes show that vegan and vegetarian diets often result in weight loss and improved A1C. A large meta-analysis showed that vegetarian dietary patterns have positive results on several measures of glucose metabolism and other markers of health, including weight, waist circumference, and LDL cholesterol.

Low-Fat Eating Patterns

Low-fat diets are not nearly as popular as they were a generation ago, but they can still work for weight loss because they restrict calories so effectively. These eating patterns can be tricky for diabetes, however, because low-fat diets are almost invariably high in carbohydrates.

For those of us watching our blood sugar levels, fat is probably the most benign of the macronutrients (although it can amplify the impact of carbohydrates and protein, the so-called  “pizza effect”). Lowering your fat consumption is not likely to help improve your blood sugar numbers, especially if you replace those calories with more carbohydrates. It is possible that low-fat diets have benefits for long-term cardiovascular health, but the evidence for that appears to be murky at this time.

With all that understood, the ADA concludes that low-fat eating patterns are not really effective in and of themselves, except to the extent that they help eaters restrict calories. Weight loss can grant comprehensive glycemic and metabolic benefits, especially for people with type 2 diabetes. But if you don’t need to lose weight, a low-fat eating pattern may be less helpful.

Low- and Very Low-Carb Eating Patterns

As explained above, low- and very low-carbohydrate eating patterns boast the most impressive results for glucose control, reducing both A1C and the need for glucose-lowering medications.

A meta-analysis of low-carb diet interventions found that participants enjoyed improved A1C, lower triglycerides, higher HDL (“good” cholesterol), and lower blood pressure in comparison to those placed on low-fat diets. Another major analysis found that “the greater the carbohydrate restriction, the greater glucose lowering.”

The long-term benefits of low-carb eating patterns are less clear — some trials have found that the improvements waned after 6-12 months — and many experts are worried about the long-term cardiovascular impact of an eating pattern that often includes a lot of saturated fat. The ADA states that the evidence we have today suggests that the diet does not increase cardiovascular risks.

Some low-carb diets restrict carbohydrate intake more than others. Very low-carb plans, which may place a limit of 25 grams of net carbohydrates per day, are often called “ketogenic” or “keto” diets because they can place the body in a state of nutritional ketosis. In this state, the body manufactures ketone bodies for energy. (This should not be confused with diabetic ketoacidosis (DKA), which is a very serious and potentially fatal condition.)

Dr. Richard Bernstein’s diet, which is extremely popular in the diabetes online community, can be considered a type of ketogenic diet that emphasizes protein rather than fat consumption.

The ADA recommends that pregnant women and people with chronic kidney disease or a history of disordered eating should avoid low-carb eating patterns.

Type 1 Diabetes

Most of the evidence discussed above deals with type 2 diabetes. It is possible that (but currently unknowable if) people with type 1 diabetes would enjoy the same kind of results using the same eating patterns. Very few trials of eating patterns in type 1 diabetes passed the ADA’s evidentiary standard.

The few studies that did pass muster were of very low-carbohydrate diets. These experiments found that very low-carb diets had impressive benefits for people with type 1, including lower A1C, lower rates of hypoglycemia, improved cholesterol, and weight loss.

There Are Healthy and Unhealthy Versions of Every Diet

No matter what framework you choose, don’t forget that every eating pattern can be done the right way and the wrong way. French fries and Pepsi are vegan. Pizza and cannolis are Mediterranean foods. American cheese is low-carb. Just because a food fits a recommended eating pattern doesn’t mean it’s actually good for you.

When designing your own diet, you should let the three pillars of diabetes eating — eat more nonstarchy vegetables, eat less sugar and refined grains, and choose whole foods over highly-processed foods — guide your decisions.

The Bottom Line

There is no “one-size-fits-all” eating plan for people with diabetes. But several alternative diets, when examined in high-quality studies, have demonstrated major metabolic benefits.

The American Diabetes Association currently recommends a number of very diets, all of which share three fundamental precepts in common:

• Eat more nonstarchy vegetables.
• Eat less sugar and refined grains.
• Choose whole foods over highly-processed foods.

If there’s a fourth fundamental lesson, it’s that carbohydrate restriction is the best way to improve glucose control.

The best diabetes diet is probably any eating pattern that lets you follow those three (or four) pillars of nutrition while remaining satisfied and happy.

Talk to your doctor about your special health concerns, and find what works for you.