【Background and purpose】Inflammatory cytokines driven from the adipose tissue and liver are involved in glucose intolerance associated with obesity. However, the changes in the progression of obese type 2 diabetes remain unknown. This study aimed to investigate the changes in chronic inflammation-related cytokines in the adipose tissue and liver focusing on progression of obesity and glucose intolerance in Otsuka Long-Evans Tokushima fatty (OLETF) rats. 【Methods】Male OLETF and Long-Evans

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... ma Otsuka (LETO) rats were used as animal models of obese type 2 diabetes and non-obese diabetes, respectively. Expression level of inflammatory cytokines (IL-6, TNFα, IL-1β, and IL-10) in the epididymal adipose tissue and liver were measured at 8, 20, 30, and 60-week-old. 【Results】For the wet weight of epididymal adipose tissue and triacylglycerol levels in the liver, the values were significantly higher in OLETF rats than in LETO rats from 8 to 30-week-old. Conversely, the values were significantly lower in OLETF rats than in LETO rats at 60-week-old. Impaired glucose tolerance was confirmed in OLETF rats at 8-week-old, and deteriorated by 60-week-old. The expression level of IL-6 in the epididymal adipose tissue of OLETF rats significantly increased from 20 to 30-week-old and significantly decreased from 30 to 60week-old. The expression level of TNFα in liver of OLETF rats significantly increased from 8 to 20-week-old and significantly decreased from 30 to 60-week-old. 【Discussion】Excessive visceral fat accumulation and increased ectopic fat could cause glucose intolerance in the early stage of type 2 diabetes. Additionally, TNFα driven from the liver and IL-6 driven from the adipose tissue could act as accelerators for glucose intolerance with progression of obesity.