BackgroundThe impact of a lifestyle intervention (LSI) program for the long-term management of subjects with metabolic syndrome in a primary care setting is not known. MethodsThis 3-year prospective controlled trial randomized adult subjects with metabolic syndrome to receive intensive LSI or to usual care in a community health centre in Malaga, Spain. LSI subjects received instruction on Mediterranean diet and a regular aerobic exercise program by their primary care professionals. Primary outcome included changes from baseline on different components of metabolic syndrome (abdominal circumference, blood pressure, HDL-cholesterol, fasting plasma glucose and triglycerides). ResultsAmong the 2,492 subjects screened, 601 subjects with metabolic syndrome (24.1%) were randomized to LSI (n=298) or to usual care (n=303); of them, a 77% and a 58%, respectively, completed the study. At the end of the study period, LSI resulted in significant differences vs. usual care in abdominal circumference (−0.4±6cm vs. +2.1±6.7cm, p<0.001), systolic blood pressure (−5.5±15mmHg vs. -0.6±19mmHg, p=0.004), diastolic blood pressure (−4.6±10mmHg vs. -0.2±13mmHg, p<0.001) and HDL-cholesterol (+4±12mg/dL vs. +2±12mg/dL, p=0.05); however, there were no differences in fasting plasma glucose and triglyceride concentration (−4±35mg/dl vs. -1±32mg/dl, p=0.43 and −0.4±83mg/dl vs. +6±113mg/dl, p=0.28). ConclusionIntensive LSI counseling provided by primary care professionals resulted in significant improvements in abdominal circumference, blood pressure and HDL-cholesterol but had limited effects on glucose and triglyceride levels in patients with metabolic syndrome.