Antidiabetic effect of black tea in type 2 diabetes model KK-A^y mice

Objectives: This study aims to investigate the diabetes prevention effects and the mechanisms by ingestion of black tea for 3 weeks in a type 2 diabetes model KK-A^y mice. Methods: The KK-A^y mice were provided black tea for 3 weeks and were examined for weight gain and diabetes condition. In addition, Gene microarray analysis was performed and gene expression in liver cells was analyzed to investigate the effect of black tea ingestion on diabetic pathology and its mechanism. Results: Black tea suppressed increase of body weight, accumulation of visceral fat, and blood glucose and insulin levels. In addition, we confirmed an improvement in insulin resistance via suppression of elevated blood glucose and insulin levels. Moreover, as a result of investigating liver gene expression by DNA microarray and real-time PCR analysis, a decreased in the expression of Fos and Jun, which are proteins comprising activator protein 1 (AP-1). Conclusions: This study suggests that long-term ingestion of black tea reduces Fos and Jun gene expression levels and is involved in suppressing worsening of diabetes.