Dietary effect of Kaempferia parviflora, a PPARγ agonist, on glucose tolerance in non‐obese type diabetic mice

Type 2 diabetes mellitus (T2DM) in Asian countries is often characterized as non‐obese type. PPARγ agonists are known to reduce adipocyte size and improve adiponectin secretion and insulin resistance, but to induce abdominal fat accumulation as an adverse effect. Search for PPARγ agonists which have little adverse effects from natural food resources is desirable for people with non‐obese T2DM. We previously showed that Kaempferia parviflora (black ginger, BG) and its ethanol extract (BGE) had PPARγ agonistic activities in a binding study, and exerted a beneficial impact on adiponectin secretion in an animal study. Although some studies showed anti‐T2DM effects of BG in diet‐induced obesity animal model, little is known to have suppressive effect of BG and BGE on T2DM in non‐obese T2DM model. We here investigated the effect of BG and BGE in diet on glucose tolerance in NSY mice with non‐obese T2DM. Male NSY mice were divided into five dietary groups and fed each diet for 8 weeks; mice fed an AIN‐93G diet (N‐LF), high‐fat and high‐sucrose diet (HF), HF diet supplemented with BG (1%) (BG), and HF diet supplemented with BGE (0.19%) (BGE). Half of mice in HF group were treated with pioglitazone (3 mg/kg) as PPARγ agonistic positive control (PIO). ICR mice fed the LF diet are used as non‐diabetic control (I‐LF). At the end of 6th and 7th week, oral glucose and insulin tolerance tests (OGTT and ITT) were respectively carried out. In OGTT, elevation of plasma glucose level was significantly suppressed in the BG and BGE groups. In ITT, plasma glucose level was significantly lowered in the BG and BGE groups. These effects were equivalent to those of pioglitazone. In conclusion, BG and its methanol extract can be effective for prevention of insulin resistance and T2DM. Support or Funding Information This work was supported by JSPS KAKENHI Grant Number 16K21349 and Mishima Kaiun Memorial Fundation.