Treatment switch from multiple daily insulin injections to sulphonylureas in an African young adult diagnosed with HNF1A MODY: a case report.

Background: Maturity onset diabetes of the young is one of the commonest causes of monogenic diabetes and can easily be mistaken for type 1 diabetes. A diagnosis of maturity onset diabetes of the young can have direct implications for genetic counseling, family screening, and precision diabetes treatment. However, the cost of genetic testing and identifying individuals to test are the main challenges for diagnosis and management in sub-Saharan Africa. We report the very first documented case of HNF1A maturity onset diabetes of the young in the sub-Saharan African region.

Case Presentation: A 20-year-old female Black African young adult diagnosed with type 1 diabetes aged 14 presented for routine out-patient diabetes consultation. She was on multiple daily insulin injections; total combined dose 0.79 IU/kg/day with an HbA1c of 7.7%. The rest of her laboratory examinations were normal. On extended laboratory analysis, she had good residual insulin secretion with post-meal plasma C-peptide levels at 1150 pmol/L. She tested negative for glutamic acid decarboxylase (GAD65), islet antigen-2 (IA-2), and zinc transporter 8 (ZnT8) islet autoantibodies. Targeted next-generation sequencing (t-NGS) for monogenic diabetes was performed using DNA extracted from a buccal sample. She was diagnosed with HNF1A maturity onset diabetes of the young, with the c.607C > T; p.(Arg203Cys) pathogenic variant, which has never been reported in sub-Saharan Africa. Her clinical practitioners provided genetic and therapeutic counseling. Within 10 months following the diagnosis of maturity onset diabetes of the young, she was successfully switched from multiple daily insulin injections to oral antidiabetic tablets (sulphonylurea) while maintaining stable glycemic control (HBA1c of 7.0%) and reducing hypoglycemia. She expressed a huge relief from the daily finger pricks for blood glucose monitoring.

Conclusion: This case reveals that HNF1A maturity onset diabetes of the young (and probably other causes of monogenic diabetes) can present in sub-Saharan Africa. A diagnosis of maturity onset diabetes of the young can have significant life-changing therapeutic implications.