Chronic glucokinase activator treatment at clinically translatable  exposures gives durable glucose lowering in two animal models of type  2 diabetes.
OBJECTIVE
Pharmacological activation of glucokinase (GK) lowers blood glucose in animal models and humans, confirming proof of concept for this mechanism. However, recent clinical evidence from chronic studies suggests that the glucose-lowering effects mediated by glucokinase activators (GKAs) are not maintained in patients with type 2 diabetes (T2D). Existing preclinical data with GKAs do not explain this loss of sustained glucose-lowering efficacy in patients. Here, we have assessed the effects of chronic (up to 11 months) treatment with two different GKAs in two models of T2D.


METHODS
Two validated animal models of T2D, insulin-resistant obese Zucker rats and hyperglycaemic gk(wt/del) mice, were treated with two different GKAs for 1 or 11 months respectively at exposures that translate to clinical exposures in humans. Blood glucose, cholesterol, triglycerides and insulin were measured. GKA pharmacokinetics were also determined.


RESULTS
Treatment with either GKA provided sustained lowering of blood glucose for up to 1 month in the Zucker rat and up to 11 months in hyperglycaemic gk(wt/del) mice, with maintained compound exposures. This efficacy was achieved without increases in plasma or hepatic triglycerides, accumulation of hepatic glycogen or impairment of glucose-stimulated insulin secretion.


CONCLUSIONS
Chronic treatment with two GKAs in two animal models of diabetes provided sustained lowering of blood glucose, in marked contrast to clinical findings. Therefore, either these animal models of T2D are not good predictors of responses in human T2D or we need a better understanding of the consequences of GK activation in humans.
D J
DJ
Baker
G P
GP
Wilkinson
A M
AM
Atkinson
H B
HB
Jones
M
M
Coghlan
A D
AD
Charles
B
B
Leighton
D000818:Animals; D001384:Azetidines / Q000494:pharmacology; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000187:drug effects* / Q000378:metabolism; D002784:Cholesterol / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics; D004195:Disease Models, Animal; D004334:Drug Administration Schedule; D004789:Enzyme Activation; D020536:Enzyme Activators / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D005941:Glucokinase / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D007328:Insulin / Q000097:blood; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D011719:Pyrazines / Q000494:pharmacology; D051381:Rats; D011924:Rats, Zucker; D013450:Sulfones / Q000494:pharmacology; D013830:Thiadiazoles / Q000494:pharmacology; D057170:Translational Research, Biomedical; D014280:Triglycerides / Q000097:blood
C561743:3-(2-methoxy-1-methylethoxy)-5-(4-methylsulfonylphenoxy)-N-(3-methyl-1,2,4-thiadiazol-5-yl)benzamide; C576407:AZD1656; D001384:Azetidines; D015415:Biomarkers; D001786:Blood Glucose; D020536:Enzyme Activators; D007004:Hypoglycemic Agents; D007328:Insulin; D011719:Pyrazines; D013450:Sulfones; D013830:Thiadiazoles; D014280:Triglycerides; D002784:Cholesterol; D005941:Glucokinase