Objective: The present study investigated the effects of long-term supplementation of alpha-mangostin (MG; a xanthone
isolated from mangosteen fruit) on hyperglycemia, and insulin resistance in type 2 diabetic rats.
Material and Method: Type 2 diabetes (DM2) was induced in male Sprague-Dawley rats by feeding high fat diet for three
weeks followed by an IP injection of low dose streptozotocin. The rats were divided into four groups: control and diabetes
without or with alpha-MG supplementation (CON, DM2, CON-MG and DM2-MG group, respectively). Alpha-MG was administered by gavage feeding in the amount of 200 mg/kg BW/day for 8 or 40 weeks. Fasting blood glucose, plasma HbA1c, cholesterol, and triglyceride were determined in all groups of rats. Serum insulin, calculated HOMA-IR and Oral glucose tolerance test were also carried out.
Results: The results showed that both 8 and 40 weeks DM2 groups had a significant increase in fasting blood glucose, HbA1c, plasma cholesterol and triglyceride compared with their aged-match control groups. Furthermore, the serum insulin and
HOMA-IR were significantly elevated in 8 weeks DM2 whereas these two parameters were significantly decreased in 40 weeks DM2 group compared with their aged-match CON groups (p<0.001). The OGTT showed impaired glucose tolerance
in DM2 groups. Interestingly, alpha-MG supplemented DM2-MG group had significantly decreased levels of fasting blood glucose, HbA1c, plasma cholesterol, triglyceride when compared with the untreated DM2 groups. Supplementation of alpha-MG for 40 weeks in DM2-MG group showed significantly increase serum insulin levels compared with that of DM2 group
(p<0.001). Moreover, alpha-MG supplemented DM-MG group demonstrated a better glucose tolerance pattern which was
different from that of DM2 group at both 8 weeks and 40 weeks experimental periods.
Conclusion: Long-term alpha-mangostin supplementation has anti-hyperglycemic, anti-hyperlipidemic effects and increase
insulin sensitivity by improving beta-cell functions in type 2 diabetes mellitus.

Keywords: Type 2 diabetes, Alpha-mangostin, Hyperglycemia, Hyperlipidemia, Insulin resistance