We performed the cohort study to evaluate the association between BMI, high-sensitivity C-reactive protein (hs-CRP) and the conversion from metabolically healthy to unhealthy phenotype in Chinese adults.

Metabolically healthy was defined as participants without history of metabolic diseases and with normal fasting blood glucose level, glycated Hb A1c level, blood pressure, lipid profile, serum uric acid level and liver ultrasonographic findings at baseline. Participants were either classified into normal weight (18·5 ≤ BMI < 24·0 kg/m2) and overweight (BMI ≥ 24·0 kg/m2) based on baseline BMI, or low (<1 mg/l) and high (≥1 mg/l) groups based on baseline hs-CRP. The conversion from metabolically healthy to unhealthy phenotype was deemed if any of the metabolic abnormalities had been confirmed twice or more during 5 years of follow-up.

Included were 4855 (1942 men and 2913 women, aged 36·0 ± 8·9 years) metabolically healthy Chinese adults. We identified 1692 participants who converted to metabolically unhealthy phenotype during the follow-up. Compared with their counterparts, the adjusted hazards ratio of the conversion was 1·19 (95 % CI 1·07, 1·33) for participants with overweight, while it was 1·15 (95 % CI 1·03, 1·29) for those with high hs-CRP level (≥1 mg/l). Further adjustment of hs-CRP did not materially change the association between BMI and the conversion. However, the association between hs-CRP and the conversion was not significant after further adjustment of BMI. The sensitivity analysis generated similar results to main analysis.

BMI was associated with the risk of the conversion from metabolically healthy to unhealthy status in Chinese adults.