Rabson-Mendenhall syndrome is characterized by severe resistance to insulin, abnormal growth and development, acanthosis nigricans, and, in some cases, a hypertrophic pineal gland. In this rare insulin receptor disorder, the patient’s body suffers from a disability to use insulin which is needed to control blood sugar levels.

Treating Rabson-Mendenhall syndrome with pharmacologic human leptin may improve the condition of the fasting hyperglycemia, hyperinsulinemia, basal glucose, and glucose and insulin tolerance.

In the very few documented cases of this extremely rare disease, young patients demonstrated skin abnormalities, dental deformities, abdominal distention, and phallic enlargement. Inflicted children were described to have coarse, senile-like faces, striking hirsutism, and early dentition. Prognathism, very thick fingernails, and acanthosis nigricans were also noted. In the case of one girl, an adult hair growth was seen at 5 years of age. Another inflicted girl was observed to have enlarged genitalia at only 6 months old, large enough to allow vaginal examination for diagnosis of a left ovarian tumor. In all these cases, the inflicted children were mentally precocious. Insulin-resistant diabetes developed in these recorded cases, resulting in the deaths of the patients during childhood due to infections.

Rabson-Mendenhall syndrome is a rare hereditary symptom transmitted via autosomal recessive pattern of inheritance. The condition often affects the children of consanguineous parents. Similar to leprechaunism, Rabson-Mendenhall syndrome results from a molecular mutation of both alleles of the insulin-receptor gene. Biologically, infants present with fasting hypoglycemia, postprandial hyperglycemia and hyperinsulinemia. The latter often progresses to permanent hyperglycemia and recurrent diabetic ketoacidosis.