These patients also had additional features and characteristics supporting T2D in addition to a GCK mutation: obesity (median BMI 36.0, IQR 34.4–37.6), older age (median age 60.5 years, IQR 45.0–63.0), and high FPG (median 9.6 mmol/l, IQR 8.8–10.2). Here, GCK is linked to obesity due to melanocortin 4 receptor deficiency.