Double diabetes as a new challenge in diabetes categorization: Case reports

Rationale: Double diabetes, characterized by the coexistence of insulin resistance and autoimmune pancreatic β-cell destruction, is often underrecognized due to overlapping features of type 1 and type 2 diabetes. Patient concerns: Two female patients presented with elevated blood sugar levels during their second trimester of pregnancy. Both required insulin therapy during pregnancy to manage hyperglycemia. Diagnoses: Initially diagnosed as gestational diabetes mellitus, further investigations postpregnancy revealed autoimmune markers such as anti-glutamic acid decarboxylase 65 positivity and low c-peptide levels, confirming type 1 diabetes in both patients along with features of insulin resistance. Interventions: Both patients were treated with insulin therapy during pregnancy. Postdelivery, one achieved blood sugar control through lifestyle modifications, while the other required continued basal-bolus insulin therapy following an episode of diabetic ketoacidosis. Outcomes: Both patients achieved glycemic control. One transitioned off insulin, while the other remained on insulin therapy. Lessons: Double diabetes can masquerade as gestational diabetes and is prone to misdiagnosis. Early identification through autoimmune testing, c-peptide levels, and clinical vigilance is critical for timely and accurate management.