Early metabolic changes in the gut leads to higher expression of intestinal alpha glucosidase and thereby causes enhanced postprandial spikes.

Aims: Prediabetes manifests several years earlier, before it progresses to diabetes. It is essential to track the earliest metabolic changes occurring in the prediabetic state and to understand the precise mechanism of how diabetes is initiated.

Main Methods: Alpha glucosidase was isolated from rat intestine and assayed using maltose as substrate. In vitro glycation of the enzyme was studied using varying fructose content through measurement of fructosamine, general and specific fluorescence. In vivo experiments were carried out through feed of 4 g fructose per day. Protein expression was studied using western blot and mRNA expression using RT-PCR method.

Key Findings: Fructose inhibits alpha glucosidase to the extent of 48.97% in 4 h at 2.5 M concentration. In vivo studies demonstrated an inhibition of 56.96% in three days. Activity was found to rise by seven days and normalized by 10 days. Protein expression was found to increase by 10.56 fold and SI mRNA by 41.84 fold on 10 days of fructose feed. Long term fructose feed for 60 days demonstrated increase in alpha glucosidase activity by 2.12 fold and increase in postprandial glucose spike.

Significance: Glycation of alpha glucosidase causes inhibition of the enzyme activity leading to compensation through higher protein expression. Long term fructose feed leads to more than two fold increase in enzyme activity causing postprandial spikes and ultimately manifesting as diabetes mellitus.