A specific and highly sensitive time-resolved fluoroimmunoassay for human proinsulin

Area of Science:

• Biochemistry
• Immunology
• Endocrinology

Background:

• Proinsulin is a precursor to insulin and its levels can indicate pancreatic beta-cell function.
• Accurate measurement of proinsulin is crucial for understanding insulin resistance and diabetes mellitus.
• Existing assays may have limitations in specificity or sensitivity for proinsulin measurement.

Purpose of the Study:

• To develop and validate a novel time-resolved fluoroimmunoassay for human proinsulin.
• To assess proinsulin concentrations in various glucose tolerance states.
• To investigate the relationship between proinsulin levels, obesity, and glucose metabolism.

Main Methods:

• Development of a time-resolved fluoroimmunoassay using two high-affinity monoclonal antibodies.
• Assay validation for specificity, detection limit, and intra-assay variation.
• Serum proinsulin analysis in 50 subjects undergoing oral glucose tolerance tests, including controls and patients with type II diabetes mellitus.

Main Results:

• The developed assay demonstrated high specificity for intact proinsulin with a low detection limit (0.1 pmol/l) and minimal cross-reactivity.
• Fasting serum proinsulin levels in non-obese controls were lower than previously reported.
• Proinsulin levels significantly increased with obesity and elevated glucose levels, correlating with insulin resistance.

Conclusions:

• The novel fluoroimmunoassay provides a sensitive and specific method for human proinsulin quantification.
• Elevated proinsulin levels are associated with obesity and hyperglycemia, suggesting a role in insulin resistance.
• This assay can be a valuable tool for research in diabetes and metabolic disorders.