The purpose of our study is to examine the influence of indoor thermal environments on health impact at home by analyzing occupants' lifestyles. We conducted investigations, surveying temperature-humidity, diabetes, cardiovascular diseases with onset risk, targeting inhabitants in the Kanto area who had signed an electric contract with Tokyo Electric Power (TEPCO). Upon inspection, we grasped the actual situation of the residence environment and monitored the participants' health conditions. Inspection was conducted using statistical analysis based on the provided data. First, we conducted univariate analysis to approximately grasp the correlation with illness onset risk, followed by a multivariate analysis after considering other factors. Results of the multivariate analysis revealed that risk of cardiovascular disease is lower if occupants maintain getting dressed in the bathroom when temperatures are higher than 18 degrees in the winter, and use air conditioners mainly at bedtime in the summer.