Background. The study aim was to examine changes in trends of presenting features during the diagnosis of patients followed up with newly diagnosed Type 1 diabetes mellitus (T1DM) over the past 24 years. Methods. The study was retrospective. Patients with a diagnosis of T1D between the years of 1996–2019 were included. Patients diagnosed in the first half of the period comprised Period I, and those from the second half comprised Period II. Patient data were extracted from medical records and included gender distribution, year of diagnosis, age at diagnosis, duration of symptoms, type of admission, frequency of diabetic ketoacidosis (DKA) and biochemical parameters. Subsequently, temporal changes in trends of these parameters were sought. Results. For the whole cohort the gender distribution was equal; 404 (49.6%) were girls and 410 (50.4%) were boys. Mean age at diagnosis was 8.5±4.2 years and age groupings at presentation were: 23.2% (n = 189) aged 0-4; 39.2% (n = 319) aged 5-9; 27.5% (n = 224) aged 10-13; 10.1% (n= 82) aged 14-18. At presentation 72 (12.7%) had hyperglycemia, 230 (40.6%) had diabetic ketosis, and 264 (46.6%) had DKA. In those with DKA, mild DKA was found in 103 (39.0%), moderate DKA in 81 (30.6%), and severe DKA in 80 (30.3%). While the frequency of DKA was 54.9% between 1996 and 2007 (Period I), this significantly decreased to 44.4% between 2008 and 2019 (Period II). Girls and boys had a similar rate of T1DM, and this did not change over time. Three peak ages of diagnosis were evident; 5-7, 8-10, 12-14 years of age. Conclusions. The frequency of DKA decreased and the frequency of admission with hyperglycemia and ketosis increased during the study period, which may have repercussions for mortality and morbidity rates and aid in improved treatment outcomes.