Diabetes mellitus constitutes a major disease burden globally, and the prevalence of diabetes continues to increase worldwide. We aimed to estimate the burden of cancer associated with type 2 diabetes mellitus in Japan between 2010 and 2030. In this study, we estimated the Population Attributable Fraction of cancer risk associated with type 2 diabetes in 2010 and 2030 using the prevalence estimates of type 2 diabetes in Japan from 1990 to 2030, summary hazard ratios of diabetes and cancer risk from a pooled analysis of eight large-scale Japanese cohort studies, observed incidence/mortality of cancer in 2010 and predicted incidence/mortality for 2030 derived from the age-period-cohort model. Our results showed that between 2010 and 2030, the total number of cancer incidence and mortality were predicted to increase by 38.9% and 10.5% in adults aged above 20 years, respectively. In the number of excess incident cancer cases associated with type 2 diabetes, an increase of 26.5% in men and 53.2% in women is expected between 2010 and 2030. The age-specific analysis showed that the population attributable fraction of cancer will increase in adults aged >60 years over time, but will not change in adults aged 20-59 years. In conclusion, this study suggests a modest but steady increase in cancers associated with type 2 diabetes.