Overview
Clinical Meaning
Prediabetes represents an intermediate state of hyperglycemia reflecting progressive insulin resistance and beta cell dysfunction that has not yet reached the diagnostic thresho...
Prediabetes represents an intermediate state of hyperglycemia reflecting progressive insulin resistance and beta-cell dysfunction that has not yet reached the diagnostic threshold for type 2 diabetes. The pathophysiology involves two concurrent defects. First, insulin resistance develops primarily in skeletal muscle, liver, and adipose tissue: excess visceral adiposity promotes chronic low-grade inflammation through adipokine dysregulation (increased TNF-alpha, IL-6, resistin; decreased adiponectin), which impairs insulin receptor substrate (IRS) phosphorylation and downstream PI3K/Akt signaling, reducing glucose transporter type 4 (GLUT4) translocation to cell membranes. In the liver, insulin resistance disinhibits hepatic gluconeogenesis, producing excessive glucose output even in the fasting state — this is the mechanism underlying impaired fasting glucose (IFG, fasting glucose 5.5–6.9 mmol/L). Second, pancreatic beta-cell compensation gradually fails: initially, beta cells compensate for peripheral insulin resistance by increasing insulin secretion (hyperinsulinemia), maintaining near-normal glucose levels for years. Over time, beta-cell mass declines through glucotoxicity, lipotoxicity, and amyloid deposition (islet amyloid polypeptide, or amylin, co-secreted with insulin forms toxic oligomers that induce beta-cell apoptosis). By the time of prediabetes diagnosis, approximately 50-80% of beta-cell function has already been lost. Impaired glucose...
