Insulin-Induced Lipoatrophy

Insulin induced lipoatrophy is localised loss of subcutaneous fat at, or occasionally away from, insulin injection or infusion sites, producing visible depressions and erratic insulin absorption.

It is now uncommon with human and analogue insulins and more frequent with older animal derived insulins. It affects women and children more often, and is reported with insulin pumps.

Associations are other autoimmune disease and insulin antibodies. It has been reported with all insulin types, including rapid acting analogues.

Pathophysiology.

An immune mechanism is proposed: local immune complex deposition, complement activation and lymphocytic infiltration of fat, probably triggered by insulin or additives.

Absorption from affected areas is irregular, so glucose control is poorer.

• Painless, circumscribed depressions at injection sites, sometimes distant from them.
• Cosmetic concern, glycaemic variability and sometimes unexplained hypoglycaemia.

• Clinical, from inspection and palpation of all injection sites.
• Biopsy is rarely needed and shows fat loss with lymphocytes and complement.
• Insulin antibody titre is not needed for diagnosis.

Differential diagnosis.

• Lipohypertrophy (the opposite finding) and normal lipodystrophy from rotation.
• Generalised or partial acquired lipodystrophy and HIV-related lipodystrophy.
• Localised scleroderma, panniculitis and corticosteroid atrophy.
• Pressure atrophy.

• Stop injecting into affected areas. Rotate into normal tissue and use new needles each injection.
• Change insulin preparation (for example from analogue to human insulin, or the reverse) if lipoatrophy persists. Evidence is limited.
• Pump users: rotate sites, and consider steel cannulae or a different infusion set.
• Topical or intralesional corticosteroid and corticosteroid added to insulin have been reported but are not established; use only on specialist advice.
• Cosmetic correction (autologous fat transfer or filler) only after the process has settled.
• Reduce insulin dose when moving to normal tissue and monitor for hypoglycaemia.

Monitoring. Examine sites at each visit and review glucose after any change.

Referral and escalation. Diabetes specialist team. Plastic surgery or dermatology for cosmetic correction.