The study, published in Diabetologia and presented at this year's annual meeting of the European Association for the Study of Diabetes (EASD), suggests that that a high protein diet improves blood sugar control in people with type 2 diabetes without any adverse effects on kidney function.
Led by Mariya Markova, from the German Institute of Human Nutrition (DIfE) at Charité University Medicine, the team compared the effects of two high-protein diets with the same number of calories – one from animal protein (AP) and one from plant protein (PP) – on metabolic functioning and liver fat.
They found that liver enzyme tests improved after intervention in both groups, and both liver fat and HbA1c were reduced in all participants – suggesting that a high protein diet improves blood sugar control in diabetic patients irrespective of whether it is from animal or plant sources.
“On molecular level, we observed the dietary-induced increase of the phosphorylation of some proteins of Akt/mTOR pathway in subcutaneous adipose tissue, but not in blood cells, indicating a differential modulation of intracellular signalling pathways,” wrote the team.
Markova and colleagues performed the randomised clinical trial in a total of 37 people (24 men, 13 women) with type 2 diabetes.
The team were randomised to receive either high-animal (meat and dairy foods) or high-plant (dietary pulses) protein diet (30% protein, 40% carbohydrates, 30% fat) for 6 weeks.
Before and after the diet intervention, various tests were completed to measure the above parameters.
"The 6-week high-protein diet leads to an improvement in glucose metabolism and decrease in liver fat independently from the protein source,” said the team. “The high-protein diet has no adverse effects on kidney parameters, moreover the kidney function actually improved in the plant protein group."
While both the plant and animal protein groups witnessed beneficial changes in blood sugar management, insulin sensitivity improved only in the animal protein group – while there was a significant reduction of plasma creatinine (meaning better kidney function) and an improvement in general kidney function (as measured by glomerular filtration rate) in the plant protein group, which was not found in the animal protein group.
The authors say that long-term observational studies with a much bigger cohort are now needed to confirm their findings.
They are now looking at the expression of key genes involved fat metabolism, glucose metabolism, inflammation in blood cells and in adipose tissue to see if there are any diet-induced alterations and to understand the effect of the higher amino acid uptake at the molecular level.
Abstracts of 51st EASD Annual Meeting
Published online, doi: 10.1007/s00125-015-3687-4
“Metabolic and molecular effects of a high-protein diet in subjects with type 2 diabetes”
Authors: M. Markova1, et al
Clinical Trial Registration Number: NCT02402985