Longitudinal Branched-Chain Amino Acids, Lifestyle Intervention, and Type 2 Diabetes in the Finnish Diabetes Prevention Study

CONTEXT: Circulating branched-chain amino acids (BCAAs) are associated with the risk of type 2 diabetes (T2D). OBJECTIVE: We examined to what extent lifestyle intervention aiming to prevent T2D interacts with this association and how BCAA concentrations change during the intervention. METHODS: We computed trajectory clusters by k-means clustering of serum fasting BCAAs analyzed annually by mass spectrometry during a 4-year intervention. We investigated whether baseline BCAAs, BCAA trajectories, and BCAA change trajectories predicted T2D and whether BCAAs predicted T2D differently in the intervention (n = 198) and control group (n = 196). RESULTS: Elevated baseline BCAAs predicted the incidence of T2D in the control group (hazard ratio [HR] 1.05 per 10 μmol/L, P = 0.01), but not in the intervention group. BCAA concentration decreased during the first year in the whole cohort (mean −14.9 μmol/L, P < 0.001), with no significant difference between the groups. We identified 5 BCAA trajectory clusters and 5 trajectory clusters for the change in BCAAs. Trajectories with high mean BCAA levels were associated with an increased HR for T2D compared with the trajectory with low BCAA levels (trajectory with highest vs lowest BCAA, HR 4.0; P = 0.01). A trajectory with increasing BCAA levels had a higher HR for T2D compared with decreasing trajectory in the intervention group only (HR 25.4, P < 0.001). CONCLUSION: Lifestyle intervention modified the association of the baseline BCAA concentration and BCAA trajectories with the incidence of T2D. Our study adds to the accumulating evidence on the mechanisms behind the effect of lifestyle changes on the risk of T2D.