INS and type 2 diabetes mellitus: High intensity interval training (HIIT) interventions lasting more than 2 weeks, compared to no exercise, reduced insulin resistance by an SMD of − 0.49 (95% CI − 0.87, − 0.12) in all groups, by − 0.38 (95% CI − 1.39, 0.63) in overweight/obese, and by − 0.62 (95% CI − 1.10, − 0.14) in people with type 2 diabetes [89].