Decreased expression of hepatic glucokinase in type 2 diabetes.
OBJECTIVE
Increased endogenous glucose production is a hallmark of type 2 diabetes. Evidence from animal models has suggested that a likely cause of this is increased mRNA expression of glucose 6-phosphatase and phosphoenolpyruvate carboxykinase (encoded by G6PC, PCK1 and PCK2). But another contributing factor may be decreased liver glucokinase (encoded by GCK).


METHODS
We examined expression of these enzymes in liver biopsies from 12 nondiabetic and 28 diabetic individuals. Diabetic patients were further separated into those with HbA1c lower or higher than 7.0.


RESULTS
In diabetic subjects with HbA1c > 7.0, we found that gluconeogenic enzymes were expressed normally, but GCK was suppressed more than 60%. Moreover, HbA1c and fasting glucose were negatively correlated with GCK, but showed no correlation with G6PC, PCK1, or PCK2.


CONCLUSIONS
These findings suggest an underlying dysregulation of hepatic GCK expression during frank diabetes, which has implications for the therapeutic use of glucokinase activators in this population.
Columbia University, Department of Pathology and Cell Biology, New York, NY, USA.
Rebecca A
RA
Haeusler
Department of Clinical and Experimental Medicine, University of Pisa School of Medicine, Pisa, Italy.
Stefania
S
Camastra
Department of Clinical and Experimental Medicine, University of Pisa School of Medicine, Pisa, Italy.
Brenno
B
Astiarraga
Department of Clinical and Experimental Medicine, University of Pisa School of Medicine, Pisa, Italy.
Monica
M
Nannipieri
Division of Bariatric Surgery, Santa Chiara Hospital, Pisa, Italy.
Marco
M
Anselmino
Department of Clinical and Experimental Medicine, University of Pisa School of Medicine, Pisa, Italy ; CNR Institute of Clinical Physiology, Italy.
Ele
E
Ferrannini
Diabetes; Glucokinase; Humans