Type 2 diabetes mellitus (T2D) represents a significant public health challenge, with a substantial impact on healthcare costs. Medical nutrition therapy is a cornerstone of T2D management, aiming to improve outcomes and reduce costs. Diet has the potential to be a powerful and cost-effective tool for treatment of type 2 diabetes mellitus (T2D), and high-protein diets have emerged as a promising approach. This article explores the effectiveness of high-protein diets in managing T2D, examining their impact on glycemic control, weight management, and overall health.
The Role of Protein in Diabetes Management
Eating a balanced diet, which includes carbohydrates, healthy fats, vegetables, fruits-and protein-is key for maintaining overall health and keeping your blood glucose (blood sugar) in target range. Protein offers several benefits for the body and diabetes management, including maintaining muscle mass, healing wounds, and aiding in weight loss and blood glucose management.
Maintaining Muscle Mass
Diabetes increases the risk of muscle loss, particularly with age. Protein plays a vital role in building and repairing muscle tissue, preventing mobility issues that may limit physical activity.
Promoting Wound Healing
Individuals with diabetes often experience impaired blood flow and elevated blood glucose levels, increasing the risk of slow-healing wounds. Protein assists in skin and tissue repair, facilitating faster wound healing and minimizing complications like foot ulcers.
Weight Loss and Blood Glucose Control
Combining protein with fiber-rich carbohydrates during meals promotes satiety, reducing the likelihood of overeating and slowing the rise of blood glucose. This can aid in weight loss, improve insulin sensitivity, lower blood glucose levels, and prevent further complications of diabetes.
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How Much Protein Should Someone with Diabetes Eat?
For people with and without diabetes, it’s generally recommended to eat about 0.8 grams of protein per one kilogram (or a little over two pounds) of body weight.
However, the amount of protein you should eat depends on your activity level, gender, muscle mass, and any health conditions, such as kidney disease. If you have kidney disease, the amount you should eat may decrease to .6 grams per kilogram of body weight per day. To learn the amount that’s best for you, talk to your doctor or registered dietitian.
Defining High-Protein Diets
There is no consensus on a definition for a high-protein diet, with a wide range of protein intakes cited in previous literature. The typical diet in the United States contains 14-16% of total energy intake as protein. A high-protein diet was defined as any diet with protein intake greater than a typical diet in the United States (>16% of total energy). Most tested diets had a protein content of around 30% of total energy.
Evidence from Clinical Studies
A systematic review was conducted to evaluate whether high-protein diets improve glycemic outcomes in people with T2D. A total of 21 independent articles met the inclusion criteria. Included articles described clinical studies designed to test a high-protein diet pattern for treatment of T2D in human participants.
Proof-of-Concept Studies
Fourteen studies were included in this group. Of these, 8 provided evidence that a high-protein diet has glycemic benefit for participants with T2D. Seven of the 8 included a protein content of ≥30% of total energy for the high-protein diet intervention, with control diets ranging from 15% to 20% of total energy as protein.
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A group of small, randomized crossover studies demonstrated the efficacy and tolerability of a specific high-protein diet they termed the Low Biologically Available Glucose (LoBAG) diet for treatment of T2D. This diet was composed of 30% of energy as protein, 30-50% of energy as fat, and 20-40% of energy as carbohydrate, with emphasis on nonstarch choices. All 4 studies showed significant improvement in glycemic control with the high-protein diet, a result that was not seen after the control diet (when a control was present).
Four of the 14 proof-of-concept studies showed benefit with a high-protein diet and with a control diet, with no difference between groups. Finally, of the 14 studies included in the proof-of-concept group, 2 studies did not demonstrate any glycemic benefit with a high-protein diet.
In summary, this group of studies overall provides efficacy data for the use of high-protein diets for glycemic management in T2D, particularly when the protein content of the intervention diet was at least 30% of total energy intake. Strengths of many of the studies in this group were rigorous control, crossover design, and high participant compliance with diet and with study procedures. Small size and short duration were limitations.
Randomized Controlled Trials
Seven randomized controlled parallel design trials evaluated the utility of high-protein diet prescriptions. Randomized controlled trials tended to be larger and longer, and had mixed results, with many trials showing no difference between a high-protein diet and control. Many randomized controlled trials were limited by low compliance and high dropout rates >15%.
Potential Benefits of High-Protein Diets
Higher-protein diets have been shown to promote satiety through increases in anorexigenic, and decreases in orexigenic, hormones. Animal and human studies have provided a mechanistic basis for efficacy, showing increased insulin and decreased postprandial glucose after protein administration.
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Protein and Blood Glucose Levels
Although protein itself does not directly raise blood glucose levels, eating a lot of it (over 75 grams per meal) can cause a slight increase in blood glucose levels three to five hours after eating. According to the American Diabetes Association’s Standards of Care in Diabetes, there is no “best” amount of protein that will help with blood glucose management or heart disease risk.
Best Protein Sources for People with Diabetes
Nutrient-dense, heart-healthy foods are the best protein sources for people with diabetes. Here are some excellent options:
- Lean meats and fish: Lean poultry (such as chicken or turkey breast without skin) and fish are low in saturated fat, which is beneficial for heart health. A 3-ounce portion of baked salmon provides around 17 grams of protein and is a good source of heart-healthy omega-3 fatty acids.
- Eggs: One large egg provides 6 grams of protein and makes for a convenient snack or side to a complete meal. Choose egg whites or cholesterol-free egg products if you are concerned about cholesterol.
- Dairy: Low- or non-fat Greek yogurt (5.5 ounces) offers 16 grams of protein. Choose the plain variety to avoid added sugars.
- Plant-based proteins: If you want to avoid meat or are looking to add more plant-based foods to your diet, try getting your protein from beans, lentils, tofu, and edamame. These protein sources also add more fiber, which may help further manage blood glucose. A half-cup of cooked lentils provides about 9 grams of protein and 8 grams of fiber. Nut butters, such as almond or peanut butter, are also great options, but be sure to select varieties without added sugars.
Plant-Based Proteins
Plant-based protein foods provide quality protein, healthy fats and fiber. They vary in how much fat and carbohydrate they contain, so make sure to read labels.
Beans such as black, kidney and pinto Bean products like baked beans and refried beans Hummus and falafel Lentils such as brown, green or yellow Peas such as black-eyed or split peas Edamame Soy nuts Nuts and spreads like almond butter, cashew butter or peanut butter Tempeh, tofu Products like meatless "chicken" nuggets, "beef" crumbles, "burgers", "bacon", "sausage" and "hot dogs"
Fish and Seafood
Try to include fish at least two times per week. Fish high in omega-3 fatty acids like Albacore tuna, herring, mackerel, rainbow trout, sardines and salmon Other fish including catfish, cod, flounder, haddock, halibut, orange roughy and tilapia Shellfish including clams, crab, imitation shellfish, lobster, scallops, shrimp and oysters.
Poultry
Choose poultry without the skin for less saturated fat and cholesterol. Chicken Turkey Cornish hen
Cheese and eggs
Reduced-fat cheese or regular cheese in small amounts Cottage cheese Whole eggs
Game
Buffalo, ostrich, rabbit or venison Dove, duck, goose or pheasant (no skin)
Beef, pork, veal and lamb
It’s best to limit your intake of red meat which is often higher in saturated fat and processed meats like ham, bacon and hot dogs which are often higher in saturated fat and sodium.
Tips for Balancing Protein in Your Diet
To maintain a balanced intake of protein, use the Diabetes Plate as a guide. Aim to fill one-quarter of your plate with lean protein at each meal. A 3-ounce portion of lean meat is roughly the size of a deck of cards and provides about 21 grams of protein. Pairing protein with fiber-rich carbs like leafy greens or whole grains may improve blood glucose management and promote fullness.
Plant vs. Animal Protein
Importantly, the wide range of potential dietary protein sources must be considered, as several studies have reported an increased risk of diabetes with animal protein consumption. Various epidemiological studies have consistently reported associations between high animal protein intake, weight gain, and, as a result, an increased risk of obesity. No protective or adverse associations have been observed with plant protein consumption. Most studies have observed that long-term animal protein consumption increases the risk of diabetes, whereas plant proteins have neutral or protective effects.
Dietary Protein Food Patterns and T2DM
Subjects were categorized into three different dietary protein food patterns, whose name were determined by the highest percentage of intake from one or two food groups. Compared to other groups, the “legumes and seafood” dietary pattern presented with a relatively higher protein intake from legumes, seafood, nuts and seeds, coarse cereals, fruits, poultry, dairy, and eggs. Subgroup analysis of the association between protein intake and T2DM by dietary protein food patterns were conducted to explore the relation between energy-adjusted protein intake with prevalence of T2DM in mutually exclusive subjects with different dietary preferences.
Potential Risks and Considerations
Many studies supporting the use of high-protein diets for patients with T2D, but were limited by small size and short duration. There were no consistent beneficial or detrimental effects of high-protein diets on renal or cardiovascular outcomes. Evidence was insufficient to recommend 1 type of protein (plant or animal) over the other.