Introducción: Este estudio analiza las características que presentan los pacientes con diabetes mellitus tipo 1 de inicio en no pediátrica, en el momento del diagnostico, en el Área de Salud de Badajoz. Desarrollo teórico: Se analizaron retrospectivamente los datos del ingreso hospitalario de 301 pacientes adolescentes y adultos diagnosticados de diabetes mellitus tipo 1 entre 1993 y 2011. En los pacientes que continuaron el seguimiento en Consultas Externas, se analizó el comportamiento de la diabetes a lo largo de los años de evolución posteriores al diagnóstico. En un subgrupo de los pacientes incluidos en el estudio se indicó la realización de una monitorización continua de glucosa en un momento dado de la evolución. Se analizaron los datos derivados de dicha monitorización y se calcularon diferentes parámetros de variabilidad glucémica.Conclusiones: Encontramos un predominio del sexo masculino, un patrón estacional con mayor incidencia de casos en los meses más fríos y una alta frecuencia de eventos estresantes e infecciosos antes del diagnóstico. En los últimos años objetivamos un aumento en la edad y la HbA1c en el diagnóstico y en el número de casos diagnosticados y una reducción en la frecuencia de pacientes diagnosticados con cetoacidosis diabética. El sexo femenino y el diagnóstico en edades más jóvenes se relacionaron con mayores necesidades de insulina durante el transcurso de la diabetes. La presencia de autoinmunidad pancreática y de tipaje HLA de riesgo fueron predictores de un mal control glucémico. La reserva pancreática menor y la mayor descompensación metabólica en el diagnóstico se relacionaron con mayores necesidades de insulina y peor control glucémico. 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