In the subgroup analysis of sample source of betatrophin, the difference of betatrophin levels between the GDM participants and controls was not statistically significant for the measurement of betatrophin from serum (SMD = 0.72; 95% CI: -0.18–1.63, P = 0.120); however, the difference was considered significant for the measurement of betatrophin from plasma (SMD = 1.5; 95% CI: 1–1.99, P < 0.010). This evidence concerns the gene ANGPTL8 and gestational diabetes.