HNF1A and type 2 diabetes mellitus: GCK‐MODY patients were younger on average than those with HNF1A‐MODY (SMD −0.39 [95% CI −0.71, −0.07] years, p = .02, n = 17; I2 = 84%, Ph <.01) or type 2 diabetes (SMD −2.26 [95% CI −4.01, −0.51] years, p = .01, n = 12; I2 = 99%, Ph <.01) at the time of diagnosis.