<i>INSR</i> gene mutation masquerading as type 1 diabetes – A case report

We report a 16-year-old girl diagnosed with a heterozygous mutation in INSR gene leading to monogenic insulin resistance diabetes. She was treated as type 1 diabetes for 2 years before the final diagnosis. Possibility of other types of diabetes should be considered in a child or an adolescent with negative autoantibodies when there is a significant family history of youth-onset diabetes in previous generations, early onset (&lt;6–12 months of age), and unusually high or low requirement of insulin, other syndromic features, or history of use of drugs such as glucocorticoids or tacrolimus. Metformin therapy led to improved glycemic control, reduced insulin need, as well as improvement in secondary sexual characteristics. This case highlights the importance of thorough clinical, biochemical, and need of genetic evaluation in children and adolescents with diabetes with atypical presentation.