Association of glucagon-like peptide-1 receptor-targeted imaging probe with in vivo glucagon-like peptide-1 receptor agonist glucose-lowering effects.

Aims/introduction: Glucagon-like peptide-1 receptor agonists (GLP-1RA) are used for treatment of type 2 diabetes mellitus worldwide. However, some patients do not respond well to the therapy, and caution must be taken for certain patients, including those with reduced insulin secretory capacity. Thus, it is clinically important to predict the efficacy of GLP-1RA therapy. GLP-1R-targeted imaging has recently emerged to visualize and quantify β-cells. We investigated whether GLP-1R-targeted imaging can predict the efficacy of GLP-1RA treatment.

Materials And Methods: We developed Indium-labeled exendin-4 derivative ( In-Ex4) as a GLP-1R-targeting probe. Diabetic mice were selected from NONcNZO10/LtJ male mice that were fed for different durations with 11% fat chow. After 3-week administration of dulaglutide as GLP-1RA therapy, mice with non-fasting blood glucose levels <300 mg/dL and >300 mg/dL were defined as responders and non-responders, respectively. In addition, ex vivo In-Ex4 pancreatic accumulations ( In-Ex4 pancreatic values) were examined.

Results: The non-fasting blood glucose levels after treatment were 172.5 ± 42.4 mg/dL in responders (n = 4) and 330.8 ± 20.7 mg/dL in non-responders (n = 5), respectively. Ex vivo In-Ex4 pancreatic values showed significant correlations with post-treatment glycohemoglobin and glucose area under curve during an oral glucose tolerance test (R  = 0.76 and 0.80; P < 0.01 and <0.01, respectively). The receiver operating characteristic area under curve for identifying responders by ex vivo In-Ex4 pancreatic values was 1.00 (P < 0.01).

Conclusion: Ex vivo In-Ex4 pancreatic values reflected dulaglutide efficacy, suggesting clinical possibilities for expanding GLP-1R-targeted imaging applications.