Crossing of Autoimmunity and Metabolic Dysfunction: A Case of Double Diabetes in an Algerian Adolescent

Abstract

<b>Background:</b> The rising prevalence of childhood obesity and sedentary lifestyles has blurred the traditional distinction between type 1 and type 2 diabetes. <i>Double diabetes</i> represents the coexistence of autoimmune β-cell destruction and insulin resistance, posing diagnostic and therapeutic challenges, particularly in adolescents.<br /> <b>Case presentation: </b>We report the case of a 17-year-old obese female with a three-year history of type 1 diabetes who developed marked insulin resistance and metabolic syndrome features. Despite high insulin requirements (1.6 U/kg/day), glycemic control remained poor (HbA1c 12.8%). Clinical examination revealed obesity (BMI 32.4 kg/m²) and acanthosis nigricans. Laboratory evaluation showed preserved C-peptide secretion, dyslipidemia, elevated leptin and homocysteine levels, and positivity for anti-GAD65 and islet cell antibodies, supporting the diagnosis of double diabetes.<br /> <b>Management and Outcomes:</b> A combined therapeutic strategy including optimization of basal-bolus insulin therapy, adjunctive metformin, structured nutritional intervention, and regular physical activity was implemented. Six months later, and at the stage of her transition, HbA1c decreased to 7.8%, body weight was reduced by 8 kg, daily insulin requirements decreased by 35%, and lipid parameters improved significantly.<br /> <b>Conclusion:</b> This case highlights the importance of early recognition of double diabetes in youth and demonstrates that integrated metabolic and autoimmune-targeted management can significantly improve glycemic control and cardiometabolic risk.