Seasonal Variation in Insulin Resistance in Koreans

ABSTRACT

BACKGROUND AND OBJECTIVES: There is a seasonal variation in the incidence of diabetes mellitus and cardiovascular disease. Insulin resistance is important in the development of both non-insulin dependent diabetes mellitus (Type II DM) and cardiovascular disease. Hyperinsulinemia, induced by an insulin resistant state, causes the development of a chronic inflammatory response in vascular structures, which is one of the main causes of cardiovascular disease. There have been several studies on seasonal variation in insulin resistance. Therefore, seasonal variation in insulin resistance were investigated to discover if any relationship existed. SUBJECTS AND METHODS: Korean people examined at a health care center were included. The subjects were divided into four groups, according to the season, and a homeostasis model assessment index (HOMA) calculated, as an indicator of insulin resistance, and compared between the groups. RESULTS: Using the homeostasis model assessment, the highest insulin resistance was observed during winter. Also, the body mass index and waist-hip ratio were highest during winter. CONCLUSION: Compensating for other metabolic factors (age, gender, body mass index, waist-hip ratio and season), insulin resistance was still found to be higher during winter. Seasonal variation in insulin resistance can be associated with the incidence of DM or cardiovascular disease. Therefore, a prospective study will be needed.