Objective To examine whether the fasting plasma glucose (FPG) of cynomolgus monkeys (Macacafascicularis) is significantly different between different seasons. The aim of this study was to investigate the correlationbetween FPG and seasonal temperature variation in a year, and to compare the FPG measured by a portable blood glucosemeter with that measured by an automatic biochemical analyzer. Methods Venous blood of monkeys was collected, andblood glucose values of monkeys in different seasons were measured by an automatic biochemical analyzer and portableblood glucose meter. Results FPG levels in cynomolgus monkeys peaked in the winter, reached the lowest level in thesummer, and fluctuated within this range during spring and autumn. Changes in FPG levels during the periods winter→spring and summer→autumn were higher than the periods autumn→winter and spring→summer, with the amplitudechanges of approximately 0. 20 mmol/ L per℃ and 0. 06 mmol/ L per℃, respectively. The differences between FPGmeasured by portable blood glucose meter and automatic biochemical analyzer were in accordance with national standards,indicating that the portable blood glucose meter can be used to detect FPG in cynomolgus monkeys. Conclusions Theresults of this study demonstrate the association of FPG with seasonal temperature variation in cynomolgus monkeys and provide a reasonable analysis of the data in future animal experiments.