The unit of measurement for cholesterol is milligrams per deciliter (mg/dL). Adults with total cholesterol levels less than 200 mg/dL are generally considered healthy. Blood sugar levels of 240 mg/dL are considered dangerously high. LDL cholesterol levels should be under 100 milligrams per deciliter (mg/dL). 160 mg/dL of LDL cholesterol is considered high. HDL levels should be at least 60 milligrams per deciliter (mg/dL). Low HDL levels of 40 mg/dL or below are linked to an increased risk of heart disease.