The effects of soya consumption on glycemic parameters of type 2 diabetes: potential for functional foods

With the rising prevalence of obesity, the incidence of type 2 diabetes mellitus (T2DM) has been steadily increasing globally over the last three decades. T2DM is characterized by elevated blood glucose levels associated with insulin resistance. Elevated blood glucose is associated with the formation of glycated hemoglobin (HbA1c) and other advanced glycation end products which may cause oxidative stress. Hyperglycemia leads to increased production of reactive oxygen species resulting in high levels of oxidative stress and inflammation. Evidence suggests that dietary interventions can improve diabetes outcomes. Soya (Glycine max L.) has been an important legume food crop for many millennia. The seed contains 30%–50% protein and 14%–24% unsaturated oil with considerable amount (>50%) of polyunsaturated fatty acids. In this chapter, we review some of the evidence linking soya intake, in particular soya protein and isoflavones, to glycaemic markers of T2DM from epidemiological and intervention trials, highlighting the importance of study design to the interpretation of results. We discuss potential mechanisms of action and the links to inflammation. We review strategies to integrate soya into functional foods for T2DM.