Type B Insulin Resistance Syndrome

Pathophysiology

The syndrome results from anti-insulin receptor antibodies that bind to the insulin receptor, thereby blocking insulin from binding to its receptor in target tissues 1, 2
This represents an extreme state of insulin resistance distinct from genetic defects in the insulin receptor itself (Type A insulin resistance) 1, 3
In some cases, these same antibodies can paradoxically act as insulin agonists after binding to the receptor, causing hypoglycemia rather than hyperglycemia 2

Patients with Type B insulin resistance syndrome typically present with severe, refractory hyperglycemia, acanthosis nigricans, and hyperandrogenism in women, including virilization and enlarged, cystic ovaries 1, 2, 3
Acanthosis nigricans (dark, velvety skin changes, particularly in body folds) is nearly universal in patients with this syndrome 1, 2
Hyperandrogenism in women is a common feature of the syndrome, including virilization and enlarged, cystic ovaries 1, 3

The syndrome is frequently found in patients with systemic lupus erythematosus and other autoimmune diseases 1, 2

The syndrome was previously termed "type B insulin resistance" to distinguish it from type A insulin resistance (genetic insulin receptor mutations) 1, 2, 3
The nomenclature reflects the autoimmune etiology (antibody-mediated) versus genetic receptor defects 1