At high dietary carbohydrate content , the low - compared with high-glycemic index level decreased insulin sensitivity from 8.9 to 7.1 units ( -20 % , P = .002 ) ; increased LDL cholesterol from 139 to 147 mg/dL ( 6 % , P. 001 ) ; and did not affect levels of HDL cholesterol , triglycerides , or blood pressure .