Endocrine Abstracts

Background: Bilateral cataracts are rarely the initial symptom of diabetes mellitus (DM). Patients with DM who developed cataracts usually have DM for many years. The prevalence of early cataracts in paediatric DM ranges between 0.7 and 3.4%. We report a case of DM diagnosis following onset of blindness due to new bilateral cataracts.

Case description: 13-year-old Caucasian girl presented with rapidly declining vision for 2 months. She was blind 2 weeks prior to presentation. Examination showed significant posterior subcapsular cataracts and visual acuity of 1/60 bilaterally. Urgent cataract surgery was scheduled. 3 days before surgery, she attended emergency department with HbA1c of >146 mmol/mol and polydipsia for 7 weeks. Blood glucose was 27.8 mmol/l; ketone was raised at 1.9 mmol/l but she was not in diabetic ketoacidosis. She had no dysmorphic features and no acanthosis nigricans. Her BMI was 26.1. Anti-GAD, anti-IA2, and anti-ZnT8 were negative. C-peptide level was high at 813 pmol/l. There is family history of type 2 diabetes (T2D). Results of her genetic testing for monogenic diabetes were normal. Child had cataract surgery with lens implant in two stages and her vision improved significantly.

Discussion: The aetiology of early cataract in children with diabetes is unknown. Several theories include osmotic damage to lens structure, polyol pathway and oxidative stress. It is currently unclear what type of diabetes our patient has. Though she was ketotic on presentation, the negative autoantibody profile suggests she may not have Type 1 diabetes. T2D is a possibility given her high HBA1c, family history and raised BMI. Monogenic diabetes is not typically associated with cataracts. HNF1B (MODY5) mutation was recently linked with bilateral cataracts. In 2 other cases, patients with bilateral cataracts and negative autoantibodies had PRRC2A gene mutation and a de novo INS gene mutation.

Conclusion: New onset bilateral cataracts are rare in children and should raise suspicion of DM or other metabolic conditions.