Metformin-induced overexpression of Maturity onset diabetes of the young (MODY)—related genes (INS, PDX1, PAX4, HNF4A, HNF1A, HNF1B, NEUROD1, GCK) coding for transcription factors and regulators of β-cell function was observed in both main comparisons (M10h vs M0, M7d vs M0), but not in the contrast M7d vs M10h, suggesting that these alterations are likely to be associated with metformin intervention rather than discrepancies between fasting and feasting states at the time points of blood collection. Here, GCK is linked to type 2 diabetes mellitus.