Elevated cholesterol and glucose are known independent risk factors for coronary heart disease. This study examines whether an adverse synergistic interaction of cholesterol and glucose magnifies coronary heart disease risk among treated hypertensive patients. Subjects were hypertensive patients (n=6672) in a worksite treatment program, with entry fasting glucose <6.99 mmol/L (126 mg/dL) and total cholesterol <6.72 mmol/L (260 mg/dL) observed for mean 5.6+/-4.5 years follow-up (range 0.5 to 21.7 years). Outcome events were incident hospitalization or death due to coronary heart disease. Cox proportional hazard models were constructed for the whole sample to assess interaction and then stratified by fasting glucose categories with thresholds defined either at impaired fasting glucose (> or =6.11 mmol/L [110 mg/dL]) or upper quartile (> or =5.72 mmol/L [103 mg/dL]). An interaction product term of total cholesterol and fasting glucose as continuous variables significantly (P=0.009) improved a Cox proportional hazards model, adjusting for total cholesterol, fasting glucose, and other coronary heart disease risk factors. Adjusted hazard ratios for 3 upper total cholesterol categories (with total cholesterol <5.17 mmol/L [200 mg/dL] as reference) in the higher fasting glucose stratum were more than double the corresponding hazard ratios in the lower stratum, whether using impaired fasting glucose or upper quartile fasting glucose as the cut point. These results suggest that an adverse synergistic interaction between glucose and cholesterol magnifies coronary heart disease risk associated with total cholesterol among hypertensive patients, raising the possibility that coronary heart disease prevention might be enhanced if cholesterol intervention criteria were modified by glucose status.
