Evaluation of a New Specific Rapid Test for Intact Proinsulin

Intact proinsulin is a biomarker for pancreatic beta-cell dysfunction. Elevated intact proinsulin predicted development of type 2 diabetes and/or macrovascular events up to seven years in advance in large prospective studies on non-diabetic participants. We performed this study to evaluate a new semi-quantitative lateral flow-based point of care rapid test (POCT) for elevated intact proinsulin (cutoff: 11 pmol/l). The test requires 10 pi of capillary whole blood and produces a visual read-out after five minutes, and is best applied two hours after a glucose challenge or a meal. Health care professionals collected POCT results from sixty patients and healthy participants (33 female, 27 male, 28 type 2 diabetes, age: 53.6 14.6 years) as well as an additional venous blood sample from all participants to measure intact proinsulin using a quantitative ELISA laboratory reference method. Elevated intact proinsulin levels (>11 pmol/l) were determined in twenty-six participants by the reference method; twenty-two of these patients also tested positive using POCT (sensitivity: 85%). All thirty-four participants with low intact proinsulin levels tested negative using POCT (specificity: 100%). The test correctly detected postprandial intact proinsulin levels in 93 % of the participants tested without any false positives, so this POCT may serve as a simple screening tool in identifying patients with prevalent (beta-cell dysfunction at high risk of developing type 2 diabetes and/or macrovascular events within the next five to seven years.