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Type 2 diabetes is on the rise, and with it, associated complications, like diabetic kidney disease (DKD). Diabetic kidney disease is the primary cause of chronic kidney disease (CKD) and a leading contributor to end-stage renal disease (ESRD). Chronic kidney disease also raises your risk of heart disease.

If you have diabetes, you know that protein is essential to help stabilize your blood sugar. But there is evidence suggesting that too much protein, especially from animal sources, raises the risk of kidney disease. Plant protein, however, has been shown to prevent or slow down kidney function decline. With that said, the evidence is inconclusive, and the 2022 Kidney Disease Outcomes Quality Initiative states that there is not enough conclusive evidence to recommend one type of protein over another.

For this reason, the Initiative lumps all types together and recommends that people with diabetes or kidney disease who are not on dialysis restrict their protein intake to 0.8 g/kg of ideal body weight per day. This is also a general recommendation for people without diabetes, though that recommendation may be too low for some people.

Researchers from Taiwan wanted to take a closer look at proteins and amino acids—the building blocks of protein— and their associations with diabetic kidney disease. They published their findings in Nutrients. Let’s break down what they found.

How Was This Study Conducted?

Researchers recruited 378 participants with type 2 diabetes; half were women with an average age of 63. Based on urine tests, participants were split into two groups: those with just diabetes and those with diabetic kidney disease. Of the 378 participants, 237 were categorized as having diabetes without kidney disease, and 141 met the criteria for kidney disease. 

Through structured interviews with registered dietitians, participants completed 24-hour dietary recalls and food frequency questionnaires at baseline. From their responses, protein amount and types were calculated. They were then placed into one of three categories based on their protein consumption: less than 0.8 grams per kilogram of ideal body weight (Group 1), 0.9-1.2 g/kg (Group 2) and more than 1.3 g/kg (Group 3). 

Also at baseline, demographics like age, sex, diabetes duration and medication use were captured, along with BMI and waist circumference. Blood pressure was measured, and bloodwork was done for fasting glucose, HbA1c, total cholesterol, triglycerides, creatinine, blood urea nitrogen and microalbuminuria. Urinary albumin-to-creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR), both screenings for kidney disease, were calculated.

What Did This Study Find?

Group 1, which had the lowest overall protein intake, also had the lowest mean estimated glomerular filtration rate (eGFR) (78), followed by Group 2 (85) and Group 3 (87). Typically, a normal eGFR is 90 or higher, and 89 to 60 indicates mild loss of kidney function.

Group 1’s serum creatinine levels also suggested lower renal (kidney) function; they also had the highest fasting blood glucose levels, HbA1c (an average of blood glucose over three months) and microalbumin levels (UACR). 

Researchers then broke down types of protein into amino acids. Amino acids are what proteins are made of. There are 20 primary amino acids necessary for humans, nine of which are essential amino acids. They’re essential because we need to get them from food, as our bodies cannot make them. 

What surfaced after statistical analyses were run was that higher overall protein intake, as well as higher intake of certain amino acids—branched-chain (BCAA), aromatic (AAA) and ketogenic amino acids—were all independently associated with a lower risk of diabetic kidney disease. In particular, leucine and lysine, two essential amino acids, were most strongly associated with a lower risk of diabetic kidney disease. 

Researchers concluded that for non-dialysis-dependent chronic kidney disease patients, in addition to the recommended total protein intake, the balance of amino acid patterns should be considered. They suggest that supplementation with branched-chain amino acids and histidine, and restriction of tyrosine, methionine and glutamic acid—all amino acids found in higher concentrations in meat—may serve as nutritional strategies to support kidney function.

How Does This Apply to Real Life?

Study authors note that their findings align with previous studies, suggesting that ketogenic amino acids, in particular, leucine and lysine, may help protect against diabetic kidney disease. While found in many foods, leucine and lysine are abundant in: 

• Dairy, like milk, yogurt and cheese
• Fish and seafood
• Legumes
• Seeds and nuts
• Meat, like pork, chicken, turkey, venison, bison and lean beef
• Soy products, like tempeh, tofu and edamame
• Eggs
• Whole grains, like quinoa, buckwheat and amaranth

As you can see, it’s a nice mix of animal and plant proteins that contain these essential amino acids. Whether you have diabetes or not, it’s important to include a variety of protein-rich foods, and plant proteins are definitely worth prioritizing, as they often include fiber and healthy fats. 

If you want to incorporate more plant-based proteins but aren’t sure where to start, check out our 7-Day Vegetarian Meal Plan for Diabetes. It’s loaded with tasty, plant-based meals and snacks, with some dairy and eggs sprinkled in. 

If you have diabetes and struggle with maintaining healthy blood sugar levels, consider how much protein you’re eating. Fiber is another important nutrient for controlling blood sugar, and it works even better when combined with protein. Many sources of plant protein will offer both of those nutrients. Combining animal proteins with a plant source is another great way to get protein and fiber into your day. For example, yogurt with fruit and nuts or tuna with veggies are filling, tasty options. 

Our Expert Take

This study suggests that people with diabetes may reduce their risk of kidney disease by eating more foods containing leucine and lysine, which are ketogenic amino acids. Because a variety of foods contain these essential amino acids, there is likely something on the list you’ll enjoy. If you typically get most of your protein from meat, try to also include plant-based proteins in your meals and snacks. Eating more plants has been shown to have many benefits, including reducing disease risk, reducing belly fat and improving gut health.