Metabolic syndrome (MetS) is characterized by insulin resistance and a clustering of risk factors for both type 2 diabetes and cardiovascular diseases (CVDs). MetS and type 2 diabetes show rising prevalence worldwide. The most important modifiable risk factors for MetS and type 2 diabetes are overweight, abdominal obesity and physical inactivity, as well as dietary factors. The aim of this work was to assess 1) the prevalence of MetS and its components, 2) the effects of a lifestyle counseling program and weight change on MetS and its components, 3) the effects of leisure-time physical activity (LTPA) on the prevention and treatment of MetS, and 4) the long-term effects of lifestyle intervention on the development of type 2 diabetes.
The study population consisted of middle-aged (mean age 55 years), overweight (mean BMI 31 kg/m2) men (n = 172) and women (n = 350) with impaired glucose tolerance (IGT) taking part in the Diabetes Prevention Study (DPS) in Finland. They were randomized to an intensive, individualized lifestyle-counseling group or a standard care control group. In addition, a population-based cross-sectional subsample of individuals from the FINRISK 1992 cohort with ages ranging from 45 to 64 years was studied. In the FINRISK 1992 population, about one fourth of the men and women had a BMI over 30 kg/m2 and nearly 80% of the men and 20% of the women had abdominal obesity. MetS was found in 39% of the men and in 22% of the women. The prevalence of MetS increased with age and worsening glucose metabolism; approximately 75% of those with IGT had MetS.
In DPS, lifestyle counseling reduced the occurrence of MetS, abdominal obesity and elevated fasting glucose after the first year of intervention. Abdominal obesity and the overall prevalence of MetS were also reduced in the long term (median intervention of four years) in the intervention group compared to the control group.
Among the 386 DPS participants with MetS at baseline, the intervention resulted in significant improvement in all the MetS components at the first annual visit. By the end of the study fasting and 2-hour insulin concentration, HOMA-IR index and HDL-cholesterol were significantly improved in the intervention group compared to the control group. Nearly 50% of the individuals with MetS in the intervention group succeeded in losing > 5% of their weight by the first annual follow-up visit. The long-term results were encouraging: over 30% of the intervention group participants still had a weight loss > 5% at the end of the study. The participants in the intervention group showed a resolution of MetS over two times more often. Weight loss was the most powerful predictor of MetS resolution, as was weight gain for MetS development. Increased participation in moderate-to-vigorous physical activity and regular long-term participation in resistance training increased the likelihood of MetS resolution and decreased the likelihood of MetS development in the DPS participants. Physical activity, and resistance training more specifically, had benefits with respect to elevated plasma glucose and dyslipidemia, but improvements in abdominal obesity and blood pressure were not observed. The DPS participants were re-examined during follow-up visits for up to three years without specific intervention in this study. The median intervention and follow-up time together was 7 years. The total diabetes incidence rate was reduced by 43% in the intervention group compared to the control group.
In conclusion, a lifestyle intervention program with a comprehensive approach resulted in lifestyle changes that reduced weight and abdominal obesity and the prevalence of MetS. Long-term follow-up showed that the progression to type 2 diabetes diminished up to three years after the discontinuation of active intervention.
