Causes include Monogenic diabetes due to genetic defects affecting beta-cell function, insulin action, or mitochondrial DNA (eg, maturity-onset diabetes of youth, neonatal diabetes) Conditions that affect the pancreas (eg, cystic fibrosis, pancreatitis, hemochromatosis, pancreatectomy) Endocrinopathies (eg, Cushing syndrome, acromegaly) Drugs, most notably glucocorticoids, beta-blockers, protease inhibitors, atypical antipsychotics, immune checkpoint inhibitors, and calcineurin inhibitors Pregnancy causes some insulin resistance in all women, but only a few develop gestational diabetes.