A 14-year-old boy is found to have fasting plasma glucose of 128 mg/dL on routine testing. He is asymptomatic with BMI 22 kg/m2. His father and paternal grandfather were diagnosed with diabetes in their 20s and 30s, both managed on oral agents. HbA1c is 6.4%. Anti-GAD65 and anti-islet cell antibodies are negative. Fasting C-peptide is normal. What is the most likely diagnosis?

• A Maturity Onset Diabetes of the Young (MODY) ✓
• B Type 2 diabetes mellitus
• C Type 1 diabetes mellitus
• D Latent autoimmune diabetes in adults (LADA)

Explanation

MODY is an autosomal dominant monogenic diabetes presenting before 25 years with non-insulin dependence, absent autoantibodies, and preserved A-peptide. The vertical transmission across three generations with mild hyperglycemia and negative antibodies distinguishes it from T1DM. T2DM is less likely in a lean adolescent without acanthosis nigricans or insulin resistance markers.

Reference: Williams Textbook of Endocrinology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.