Stability of insulin and C‐peptide measurement with long‐term frozen storage of serum: Implications for diabetes research studies

The current era of large‐scale clinical trials in diabetes has generated thousands of biological samples from study participants that are being stored long‐term under frozen conditions for the future measurement of analytes of interest. Insulin and C‐peptide are two such analytes that can provide insight into underlying pathophysiological processes (insulin sensitivity and β‐cell function). However, the validity of the inferences that may be...