Effects of the amount and type of carbohydrates used in type 2 diabetes diets in animal models: A systematic review

Abstract

Type 2 diabetes mellitus (T2DM) is among the most prevalent diseases in the world, affecting over 420 million people. The disease is marked by a poor metabolic effect of insulin leading to chronic hyperglycaemia, which can result in microvascular complications. It is widely known that postprandial glycaemia is reliant on the total carbohydrate content of a meal. However, the importance of the amount and the source of these carbohydrates remains controversial due to mechanisms other than insulin secretion. Oxidative stress, inflammation, pyruvate production and the quality of the intestinal microbiota, resulting in plasma lipopolysaccharides and short-chain fatty acids production, play an important role in blood sugar control and consequently in type 2 diabetes. Thus, we systematically reviewed the preclinical evidences on the impact of the amount and type of carbohydrate found in different diets and its influence on blood glucose levels in diabetic animals. We used a comprehensive and structured search in biomedical databases Medline (PubMed), Scopus and Web of Science, recovering and analyzing 27 original studies. Results showed that sucroserich diets deteriorated diabetic condition in animal models regardless of the total dietary carbohydrate content. On the other hand, fiber, particularly resistant starch, improved blood glucose parameters through direct and indirect mechanisms, such as delayed gastric emptying and improved gut microbiota. All studies used rodents as animal models and male animals were preferred over females. Improvements in T2DM parameters in animal models were more closely related to the type of dietary carbohydrate than to its content on a diet, i. e., resistant starch seems to be the most beneficial source for maintaining normoglycemia. Results show that current literature is at high risk of bias due to neglecting experimental methods.

Chronic Effects of a High Sucrose Diet on Murine Gastrointestinal Nutrient Sensor Gene and Protein Expression Levels and Lipid Metabolism

“…The observed hyperphagia is unlikely to be responsible for the observed weight gain and metabolic disturbances, since pair fed studies using HSD and control fed rodents also reported weight gain, diabetes and hepatic steatosis [ 33 ]. Consistent with other reports, the HSD fed mice were also hyperglycaemic, but not hyperinsulinemic, suggesting the animal was diabetic due to insulin resistance and pancreatic beta cell exhaustion [ 34 , 35 , 36 ].…”

Can Enzyme‐Resistant Starch Snack Prevent Blood Glucose Fluctuations? A Pilot Trial in Patients with Insulin‐Treated Type 2 Diabetes

“…Notably, different types of carbohydrates, which play an important role in our diet, have distinct effects on BG levels. [27,28] Food items with a high glycemic index/glycemic load have a negative impact on glycemic control. [29] Carbohydrates account for approximately 50% of daily energy intake [30] in individuals who frequently include bakery products in their diets.…”

Lipidomics Reveals That Rice or Flour as a Single Source of Carbohydrates Cause Adverse Health Effects in Rats

“…These results indicated that whole grain corn powder can effectively reduce blood glucose and lipid levels ( 27 ). Some studies attribute the consumption of whole grains rich in dietary fiber to help lower blood glucose and lipid levels ( 28 ). In our research, we did not add dietary fiber or other beneficial ingredients to the control group feed.…”