For 2‐hour insulin, GCK‐MODY patients had higher insulin concentration on average compared to HNF1A‐MODY patients (SMD 0.43 [95% CI 0.22, 0.65] mIU/l, p < .001, n = 2; I2 = 0%, Ph = .56) but had lower insulin concentration compared to type 2 diabetes patients (SMD −0.57 [95% CI −0.74, −0.39] mIU/l, p < .001, n = 1). This evidence concerns the gene HNF1A and type 2 diabetes mellitus.