Aim: Diabetes mellitus is a major public health problem worldwide. Type 1 diabetes mellitus (T1DM) is the most common metabolic chronic disease in genetically susceptible children and adolescents, due to an autoimmune process characterized by a selective destruction of insulin producing β-cells. The aim is to assess the epidemiological features of new-onset T1DM in children and adolescent at the national level during the period 2010-2014 in Department of Pediatrics, Endocrine Unit, University Hospital Center 'Mother Teresa', Tirana, as the unique center for pediatric endocrinology and diabetology in Albania. Methods: The clinical and laboratory characteristics of 152 patients aged <15 years newly diagnosed with T1D from 1 January 2010 to 31 December 2014 were studied. T1D was diagnosed according to WHO 2006 criteria and DKA was diagnosed based on ISPAD 2014 criteria. Patients were classified into 3 sub-groups (I: 0-4 years, II: 5-9 years, and III; 10-14 years). Statistical analysis was performed using SPSS 26. Results: The incidence of new-onset of T1DM was 5.012/100.000/year. The mean age of children at diagnosis was 8.3 ± 3.6 years. The patients were mostly diagnosed at ages 5-9 years (40.1%), and 10-14 years (39.5%), followed by the 0-4 years age group (20.4%). Mean duration of symptoms was 23.35 ± 17.16 days; longer in the subgroup 5-9 years (P= 0. 0.013). Three quarters (75%) of children with T1DM live in urban areas. Viral infections or other circumstance triggers were in 41.9% of children aged 0-4 years compared to other subgroups (P=0.002). Most of the children were born in the spring−summer months (53.23%) compared to the autumn−winter months (46.77%). Approximately 1/4 of the children were born and diagnosed with type 1 diabetes in each of the seasons of the year and 52.63% of the patients studied were first born. Family history for DMT1 and DMT2 is observed in 15.8% and 17.8% of the children, respectively. Polyuria (99.3%), polydipsia (99.6%) and weight loss (98.1%) were the most common symptoms and 67.8% of patients presented with diabetic ketoacidosis (DKA). Misdiagnosis was in 21 (13.8%) patients. Mean glycosylated hemoglobin A1c (HbA1c) was 11.63%; 11.9 ± 2.0 in DKA positive children and 11.1 ± 2.4 in DKA negative children (p= 0.195). At diagnosis and during follow up of T1DM 25% (38/152) developed associated autoimmune diseases; 68.42% at diagnosis of T1DM and 65.79% (25/38) of patients were female. During follow up children with T1DM developed associated CD and SAT, 2.54, and 2.19 years, respectively. Conclusion: Diabetes mellitus is one of the major public health problems worldwide. Albania is a country with middle incidence of T1DM and the age at onset is decreasing. The symptoms lasted significantly longer and mean HbA1c levels were significantly higher in older children. The incidence