Figure 5.

This figure shows the pathophysiology and pathways related to the metabolic changes that occur in patients with type 1 and type 2 diabetes. High levels of branched-chain amino acids (BRAAs) are often associated with increased BMI levels (obesity) and insulin resistance (type 2 diabetes) [23,24,25]. In contrast, low levels of BRAAs are accompanied by lower BMIs and good insulin sensitivity. Thus, BRAAs appear to induce insulin resistance. Decreasing the BRAA concentration might improve life, as has been shown in obese and prediabetic mice [73]. BRAAs are synthesized from glucose via pyruvic acid. Glucose is normally used in the pentose phosphate pathway, and erythrose-4-phosphate is obtained as an intermediate product. In contrast, erythrose-4-phosphate is an important educt of the shikimic acid pathway, which is an important pathway in enteral E. coli. As a result, aromatic amino acids are produced by E. coli from erythrose-4-phosphate [11,32,72] and from glucose in patients with type 2 diabetes mellitus and high glucose concentrations [72].