P-223: Growth failure and glycaemic instability in INSR-related monogenic diabetes: a case highlighting a dual therapeutic challenge
S EL Moudden, S Abourazzak, M HidaAbstract
Introduction
Rabson–Mendenhall syndrome is an ultra-rare autosomal recessive insulin receptoropathy caused by pathogenic INSR variants. It is a severe form of monogenic diabetes combining extreme insulin resistance, acanthosis nigricans, dysmorphism and growth failure. The phenotype may mimic type 1 diabetes.
Objectives
To highlight the dual challenge of glycaemic control and growth failure in a child with genetically confirmed Rabson–Mendenhall syndrome.
Methods
We report the clinical, biochemical, auxological and genetic features of an 13 year old boy referred for poorly controlled diabetes
Results
The patient was born at term with low birth weight and neonatal hypotrophy. He had syndromic dysmorphism, severe acanthosis nigricans, ocular complications and childhood onset diabetes, initially treated as type 1 diabetes. He was admitted after marked hyperglycaemia during preoperative assessment for cataract surgery. Examination showed severe staturo-ponderal delay, height and weight around –3 SD, prepubertal status and hyperkeratotic pigmented lesions. HbA1c was 13.6%; thyroid, renal, hepatic and inflammatory work-up were normal. Bone age was delayed at 8 years. The association of insulin-resistant diabetes, acanthosis nigricans, dysmorphism and growth failure prompted molecular testing, confirming a pathogenic INSR variant. Treatment was optimized with basal-bolus insulin, metformin and therapeutic education. Glycaemic values improved, ketonuria resolved and no further ketoacidotic episodes occurred. At follow-up, the child remained clinically stable with improved fasting and postprandial glucose profiles.
Conclusions
Rabson–Mendenhall syndromeshould be considered in children labelled as type 1 diabetes when severe acanthosis nigricans, dysmorphism, growth failure and insulin-resistant hyperglycaemia coexist. Early recognition of INSR-related monogenic diabetes is essential to adapt treatment, guide genetic counselling and frame growth failure as part of a complex insulin receptor disorder.