BACKGROUND: Insulin resistance is a metabolic spectrum that progresses from hyperinsulinemia to the metabolic syndrome, impaired glucose tolerance, and finally type 2 diabetes mellitus. It is unclear when vascular abnormalities begin in this spectrum of metabolic effects. OBJECTIVE: To evaluate the association of insulin resistance with the presence and reversibility of coronary vasomotor abnormalities in young adults at low cardiovascular risk. DESIGN: Cross-sectional study followed by prospective, open-label treatment study. SETTING: University hospital. PATIENTS: 50 insulin-resistant and 22 insulin-sensitive, age-matched Mexican-American participants without glucose intolerance or traditional risk factors for or evidence of coronary artery disease. INTERVENTION: 3 months of thiazolidinedione therapy for 25 insulin-resistant patients. MEASUREMENTS: Glucose infusion rate in response to insulin infusion was used to define insulin resistance (glucose infusion rate < or = 4.00 mg/kg of body weight per minute [range, 0.90 to 3.96 mg/kg per minute]) and insulin sensitivity (glucose infusion rate > or = 7.50 mg/kg per minute [range, 7.52 to 13.92 mg/kg per minute]). Myocardial blood flow was measured by using positron emission tomography at rest, during cold pressor test (largely endothelium-dependent), and after dipyridamole administration (largely vascular smooth muscle-dependent). RESULTS: Myocardial blood flow responses to dipyridamole were similar in the insulin-sensitive and insulin-resistant groups. However, myocardial blood flow response to cold pressor test increased by 47.6% from resting values in insulin-sensitive patients and by 14.4% in insulin-resistant patients. During thiazolidinedione therapy in a subgroup of insulin-resistant patients, insulin sensitivity improved, fasting plasma insulin levels decreased, and myocardial blood flow responses to cold pressor test normalized. LIMITATIONS: The study was not randomized, and it included only 1 ethnic group. CONCLUSIONS: Insulin-resistant patients who do not have hypercholesterolemia or hypertension and do not smoke manifest coronary vasomotor abnormalities. Insulin-sensitizing thiazolidinedione therapy normalized these abnormalities. These results suggest an association between insulin resistance and abnormal coronary vasomotor function, a relationship that requires confirmation in larger studies.
BACKGROUND:Insulin resistance is a metabolic spectrum that progresses from hyperinsulinemia to the metabolic syndrome, impaired glucose tolerance, and finally type 2 diabetes mellitus. It is unclear when vascular abnormalities begin in this spectrum of metabolic effects. OBJECTIVE: To evaluate the association of insulin resistance with the presence and reversibility of coronary vasomotor abnormalities in young adults at low cardiovascular risk. DESIGN: Cross-sectional study followed by prospective, open-label treatment study. SETTING: University hospital. PATIENTS: 50 insulin-resistant and 22 insulin-sensitive, age-matched Mexican-American participants without glucose intolerance or traditional risk factors for or evidence of coronary artery disease. INTERVENTION: 3 months of thiazolidinedione therapy for 25 insulin-resistant patients. MEASUREMENTS: Glucose infusion rate in response to insulin infusion was used to define insulin resistance (glucose infusion rate < or = 4.00 mg/kg of body weight per minute [range, 0.90 to 3.96 mg/kg per minute]) and insulin sensitivity (glucose infusion rate > or = 7.50 mg/kg per minute [range, 7.52 to 13.92 mg/kg per minute]). Myocardial blood flow was measured by using positron emission tomography at rest, during cold pressor test (largely endothelium-dependent), and after dipyridamole administration (largely vascular smooth muscle-dependent). RESULTS: Myocardial blood flow responses to dipyridamole were similar in the insulin-sensitive and insulin-resistant groups. However, myocardial blood flow response to cold pressor test increased by 47.6% from resting values in insulin-sensitive patients and by 14.4% in insulin-resistant patients. During thiazolidinedione therapy in a subgroup of insulin-resistant patients, insulin sensitivity improved, fasting plasma insulin levels decreased, and myocardial blood flow responses to cold pressor test normalized. LIMITATIONS: The study was not randomized, and it included only 1 ethnic group. CONCLUSIONS:Insulin-resistant patients who do not have hypercholesterolemia or hypertension and do not smoke manifest coronary vasomotor abnormalities. Insulin-sensitizing thiazolidinedione therapy normalized these abnormalities. These results suggest an association between insulin resistance and abnormal coronary vasomotor function, a relationship that requires confirmation in larger studies.
Authors: Carl J Pepine; Keith C Ferdinand; Leslee J Shaw; Kelly Ann Light-McGroary; Rashmee U Shah; Martha Gulati; Claire Duvernoy; Mary Norine Walsh; C Noel Bairey Merz Journal: J Am Coll Cardiol Date: 2015-10-27 Impact factor: 24.094
Authors: Thomas H Schindler; Xiao-Li Zhang; Gabriella Vincenti; Leila Mhiri; René Lerch; Heinrich R Schelbert Journal: J Nucl Cardiol Date: 2007-07 Impact factor: 5.952
Authors: Bobak Heydari; Yu-Hsiang Juan; Hui Liu; Siddique Abbasi; Ravi Shah; Ron Blankstein; Michael Steigner; Michael Jerosch-Herold; Raymond Y Kwong Journal: Circ Cardiovasc Imaging Date: 2016-04 Impact factor: 7.792