The combined effect of various types of fasting significantly reduced fasting blood sugar (FBS) [standard mean difference (SMD) = -0.51; 95% confidence interval (CI): -0.81, -0.20; <i>p</i> = 0.001], insulin (SMD <i>=</i> -0.27; 95% CI: -0.52, -0.03; <i>p</i> = 0.027) and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) (SMD <i>=</i> -0.39; 95% CI: -0.65, -0.12; <i>p</i> = 0.004), and HbA1c (SMD = -0.25; 95% CI: -0.49, -0.02; <i>p</i> = 0.034) levels. This evidence concerns the gene INS and Insulin resistance.