Cline GW, et al. - Using vesicular monoamine transporter type 2 (VMAT2) tracer [¹⁸F]fluoropropyl-(+)-dihydrotetrabenazine, researchers intended to quantify beta cell mass (BCM) in humans with impaired glucose tolerance (prediabetes) or type 2 diabetes, and in healthy obese volunteers (HOV). Dynamic positron emission tomography (PET) data were obtained for 4 h with metabolite-corrected arterial blood measurement in 16 HOV, five prediabetic and 17 type 2 diabetic participants. Findings demonstrated that the observed correlations of VMAT2 density in the pancreas and pancreas regions with years since diagnosis of type 2 diabetes, glycaemic control and beta cell function pointed towards the loss of BCM contributing to deficient insulin secretion in humans with type 2 diabetes.