A 35-year-old woman has a reputation as a perfectionist. She has angina pectoris of 6 months’ duration. On physical examination, her blood pressure is 135/85 mm Hg. She is 168 cm (5 ft 5 in) tall and weighs 82 kg (BMI 29). Her Hgb A 1C is 9% and fasting serum glucose is 143 mg/dL. Coronary angiography shows 75% narrowing of the anterior descending branch of the left coronary artery and 70% narrowing of the right coronary artery. Angioplasty with stent placement is performed. Which of the following is her greatest risk factor for the causation of her disease?