Relationship between Heart Rate Reduction and Insulin Resistance in Normoglycemic Individuals

ABSTRACT

BACKGROUND AND OBJECTIVES: It is well known that, regardless of whether a person has cardiovascular diseases, the reduction of heart rate after exercise reflects the impairment of the autonomic nervous system. It is also a predictive factor of death rate and it correlates to insulin resistance. Therefore, we assessed these correlations in normoglycemic subjects. SUBJECTS AND METHODS: Exercise stress testing was performed according to the Bruce protocol. Anthropometric indices of adiposity, metabolic variables, blood pressure (BP) and several cardiovascular risk factors were measured. The HOMA index was used as the insulin resistance, and the impairment of the autonomic nervous system was assessed by measuring the reduction of heart rate for 2 minutes after the cessation of exercise. RESULTS: The reduction of heart rate during 2 minutes after the cessation of exercise statistically correlated with the HOMA index, gender, age, body mass index, the waist circumference, heart rate during rest, the maximum heart rate, serum total cholesterol concentration, serum high density lipoprotein cholesterol concentration and serum low density lipoprotein cholesterol concentration, (p<0.05). However, on multiple regression analysis, the HOMA index, gender, heart rate during rest, and the maximum heart rate significantly correlated to the reduction of heart rate during 2 minutes after the cessation of exercise. CONCLUSION: In individuals with normal serum glucose levels, even after adjustment was made for other factors, the reduction of heart rate after the cessation of exercise correlated to insulin resistance. Hence, in individuals with normal serum glucose levels, efforts to improve insulin resistance have to be made, and prospective study on this subject is required.