GCK and Hyperglycemia: The child with a novel substitution heterozygous mutation in GCK (c.364‐8T>G) had a phenotype consistent with glucokinase MODY [persistent fasting hyperglycaemia in the range 5.7–6.4 mmol/l, HbA1c 50.8 mmol/mol (6.8%) without treatment and a small postprandial increase in blood glucose evidenced by a 2‐h oral glucose tolerance test value of 7.1 mmol/l].