Insulin autoimmune syndrome
Insulin autoimmune syndrome is spontaneous hyperinsulinemic hypoglycemia in a person without prior insulin exposure, caused by high-titer autoantibodies that bind endogenous insulin and release it unpredictably, or by antibodies that directly activate the insulin receptor. First-line treatment is dietary, with small frequent low-glycemic-index meals and avoidance of any culprit drug; refractory or severe recurrent hypoglycemia is treated with prednisone 30-60 mg orally once daily, tapered over 1 to 3 months.
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What this article covers
- Overview
Antibody-mediated spontaneous hypoglycemia: endogenous hyperinsulinemic hypoglycemia caused by autoantibodies directed against insulin or the insulin receptor in a person who has never received exogenous insulin.
- Epidemiology
A rare cause of hyperinsulinemic hypoglycemia: grouped with insulinoma, non-insulinoma pancreatogenous hypoglycemia, and post-gastric-bypass hypoglycemia as uncommon causes of hypoglycemia in a person without diabetes.
- Risk factors
Any exposure that can trigger anti-insulin antibody formation: this entity is grouped with other antibody-mediated causes of hypoglycemia, and a single trigger is not established; a temporal…
- Pathophysiology
Anti-insulin antibodies bind circulating insulin and release it unpredictably: high-titer autoantibodies form immune complexes with endogenous insulin; dissociation of the complex releases free…
- Clinical features
Neuroglycopenic and hyperadrenergic symptoms of hypoglycemia: confusion, altered mental status, blurred vision, or difficulty concentrating (neuroglycopenic), together with sweating, tremor…
- Differential diagnosis
Insulinoma: elevated insulin, C-peptide, and proinsulin with suppressed beta-hydroxybutyrate during a fasting episode, but insulin antibody testing is negative, unlike insulin autoimmune syndrome, where antibodies are positive.
- Diagnosis
The clinching basis is a positive insulin antibody result in a patient with a confirmed Whipple triad and an endogenous hyperinsulinemic pattern: elevated total insulin together with elevated…
- Management
First, treat the acute hypoglycemic episode like any other, choosing the route by whether the patient can swallow safely: alert patient: 15 to 20 g fast-acting oral carbohydrate, recheck glucose in…
- Complications
Seizure, coma, and death: the most severe outcomes of uncorrected, unpredictable neuroglycopenia, made more dangerous here because episodes are not tied to a predictable trigger such as a meal or exertion.
- Prognosis
Generally self-limited: most cases resolve as the causative antibody titer declines, often without the need for indefinite treatment.
- Prevention
Educate the patient to recognize both hyperadrenergic and neuroglycopenic warning symptoms, since episode timing is unpredictable rather than tied to fasting or a fixed postprandial window.
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Related articles
- Hypoglycemia in adults
Hypoglycemia is a plasma glucose below 70 mg/dL, most often a complication of insulin or sulfonylurea therapy for diabetes, and in a person without diabetes it requires a Whipple triad-based evaluation for insulinoma or another endogenous cause. An alert patient is treated with 15 to 20 g of fast-acting oral carbohydrate, while a patient unable to swallow safely receives intramuscular glucagon 1 mg or intravenous dextrose 50% 25 g.
- Insulin therapy in diabetes mellitus
Insulin therapy replaces or supplements endogenous insulin to control hyperglycemia, and is lifelong and mandatory in type 1 diabetes because of absolute beta-cell failure, while in type 2 diabetes it is added when oral and noninjectable agents fail to reach glycemic goals. First-line therapy is a basal-bolus regimen started at 0.4-1.0 units/kg/day in type 1 diabetes, or basal insulin glargine 10 units/day (or 0.1-0.2 units/kg/day) in type 2 diabetes, titrated to a fasting glucose target.
- Type 1 diabetes mellitus
Type 1 diabetes mellitus is an insulin-deficient state from autoimmune (type 1A) or idiopathic (type 1B) destruction of pancreatic beta cells, presenting with hyperglycemia that can range from mild to life-threatening diabetic ketoacidosis. Diagnosis combines standard glycemic criteria with autoantibody testing (GAD65, IA-2), and lifelong insulin therapy, generally as a basal-bolus regimen, is required from diagnosis, with self-monitoring or continuous glucose monitoring to guide dosing.