Rare sugar d-allulose: Potential role and therapeutic monitoring in maintaining obesity and type 2 diabetes mellitus

Obesity and type 2 diabetes mellitus (T2DM) are the leading worldwide risk factors for mortality. The inextricably interlinked pathological progression from excessive weight gain, obesity, and hyperglycemia to T2DM, usually commencing from obesity, typically originates from overconsumption of sugar and high-fat diets. Although most patients require medications, T2DM is manageable or even preventable with consumption of low-calorie diet and maintaining body weight. Medicines like insulin, metformin, and thiazolidinediones that improve glycemic control; however, these are associated with weight gain, high blood pressure, and dyslipidemia. These situations warrant the attentive consideration of the role of balanced foods. Recently, we have discovered advantages of a rare sugar, d-allulose, a zero-calorie functional sweetener having strong anti-hyperlipidemic and anti-hyperglycemic effects. Study revealed that after oral administration in rats d-allulose readily entered the blood stream and was eliminated into urine within 24 h. Cell culture study showed that d-allulose enters into and leaves the intestinal enterocytes via glucose transporters GLUT5 and GLUT2, respectively. In addition to d-allulose's short-term effects, the characterization of long-term effects has been focused on preventing commencement and progression of T2DM in diabetic rats. Human trials showed that d-allulose attenuates postprandial glucose levels in healthy subjects and in borderline diabetic subjects. The anti-hyperlipidemic effect of d-allulose, combined with its anti-inflammatory actions on adipocytes, is beneficial for the prevention of both obesity and atherosclerosis and is accompanied by improvements in insulin resistance and impaired glucose tolerance. Therefore, this review presents brief discussions focusing on physiological functions and potential benefits of d-allulose on obesity and T2DM.