Endocrine Abstracts

Background: Autoantibody-negative type 1 diabetes (also named atypical diabetes, idiopathic diabetes, type 1b diabetes or “ketosis-prone” diabetes) is a heterogenous and understudied group. There is growing evidence for a subgroup of diabetes patients in Sub-Saharan African populations who are autoantibody negative with low type 1 genetic risk scoring and higher endogenous insulin production but without features of type 2 diabetes.

Case: 6-year-old boy of Somalian ethnicity presented with a 4-week history of polyuria, polydipsia and weight loss of 4-5 kg. He had an initial blood glucose of 24 mmol/l. He was ketotic (5.1 mmol/l) but not in diabetic ketoacidosis. HbA1c at diagnosis 109 mmol/mol; BMI was 16 with no acanthosis nigricans. There was a family history of diabetes (paternal aunt with type 2 diabetes and paternal second cousin diagnosed with type 1 diabetes at 18 months). He was started on a multiple daily injection regime of insulin. Insulin was stopped completely at 5 months after diagnosis, due to recurrent hypoglycaemia. He remained off insulin for 16 months and currently has a very low but increasing insulin requirement of 0.1 unit/kg/d 4 years after diagnosis. He was triple antibody negative (to glutamic acid decarboxylase (GAD), insulinoma-associated antigen 2 (IA-2), and zinc transporter 8 (ZnT8)) at diagnosis and on two further occasions. Urinary C-peptide creatinine ratio (UCPCR) at one year after diagnosis was 0.58 nmol/ mmol. Blood C-peptide level 4 years after diagnosis <94pmol/l. Exome sequencing of all known monogenic diabetes genes was negative.

Conclusion: We report a paediatric patient of Somalian ethnicity with an atypical diabetes who was ketotic at presentation, without autoimmunity and with prolonged low insulin requirement. We highlight the importance of being aware of a potentially new subgroup of children and young people with diabetes of Sub-Saharan African ancestry in the UK; further work will highlight the pathophysiology and treatment strategies for this group of patients.