Hyperglycemia markedly upregulated the expression of glycolytic enzymes (glucokinase and 6-phosphofructo-1-kinase, PFK1) 5 h following glucose administration, while at 24 h posttreatment, it increased isocitrate dehydrogenase (IDH) activity, a key enzyme of the tricarboxylic acid cycle, and the expression of lipogenic factors (PGC1β, Lpin1, and SREBP1).
Hyperglycaemia due to glucokinase deficiency is often mild (fewer than 50% of subjects have overt diabetes) and is evident during the early years of life.
Glucokinase (GCK) mutations cause a monogenic form of hyperglycaemia (GCK-MODY) characterised by fasting hyperglycaemia with low postprandial glucose excursions and a marginally elevated HbA1c.
GCK-MODY patients are typically characterized by a moderate fasting hyperglycemia; however, little is known about atherosclerosis and intermediate-related phenotypes in these subjects.
Glucokinase is inhibited in the postabsorptive state by sequestration in the nucleus bound to GKRP, and it is activated postprandially by portal hyperglycemia and fructose through dissociation from GKRP, translocation to the cytoplasm, and binding to PFK2/FBP2.
A novel glucokinase deletion (p.Lys32del) and five previously described mutations co-segregate with the phenotype of mild familial hyperglycaemia (MODY2) in Brazilian families.
At diagnosis of pediatric diabetes, absence of all islet autoantibodies and modest hyperglycemia (HbA<sub>1c</sub> <7.5% [58 mmol/mol]) should result in testing for GCK, HNF1A, and HNF4A MODY.