Proinsulin

Proinsulin is the inactive precursor molecule from which insulin is formed in the pancreas. A blood proinsulin test measures levels of this compound, which is a sensitive marker of beta cell stress and insulin resistance. Elevated fasting proinsulin—even with normal insulin and glucose levels—suggests early pancreatic dysfunction and may predict future diabetes development. This test is useful for identifying individuals at high risk for type 2 diabetes before standard tests become abnormal, enabling early intervention through lifestyle changes.