Why does bariatric surgery confer better cardiovascular benefit to diabetics?

Differential changes in fasting serum levels of fibroblast growth factor (FGF)-19 and FGF-21 may help account for the superior cardiovascular benefit of bariatric surgery on obese patients with type 2 diabetes mellitus (T2D) vs nondiabetics, a recent study has found.

Eighty obese patients who had undergone gastric bypass participated in the study. Forty (mean age 47.8 years, 57.5 percent women) had T2D, while the other half (mean age 36.6 years, 65.0 percent women) did not. The United Kingdom Prospective Diabetes Study (UKPDS) engine was used to assess CV risk before and after surgery.

Additionally, the researchers looked at five biomarkers whose levels were measured before and after surgery: FGF-19, FGF-21, corin, oxidized low-density lipoprotein (ox-LDL), and soluble receptor for advanced glycation end-products (sRAGE).

Twelve months after surgery, both groups showed significant reductions in body weight and body mass index, along with improvements in metabolic parameters such as lipid profile and inflammation markers. Both groups likewise saw a significant reduction in 10-year coronary heart disease (CHD) and fatal CHD risk after surgery, though such effect was stronger in T2D patients.

Such a difference in cardiovascular benefit could be explained by differential effects of surgery on biomarkers. In particular, mean levels of three of the five serum biomarkers changed significantly 1 year after surgery: FGF-19 (195.6 to 283.2 pg/mL; p=0.002), corin (3.3 to 4.6 ng/mL; p=0.002), and ox-LDL (148.5 to 107.9 U/L; p<0.001).

Notably, T2D patients showed a significantly larger increase in FGF-19 levels and decrease in FGF-21 levels relative to non-T2D comparators. Changes in corin and ox-LDL concentrations were not different between the groups.