Objective  To explore the clinical characteristics of adult patients with fulminant type 1 diabetes mellitus (FT1DM), a specific subtype of type 1 diabetes mellitus (T1DM).

  Methods  We collected the clinical data of patients who were admitted to West China Hospital, Sichuan University in 2010-2019 for FT1DM and type 1 diabetes mellitus (T1DM) presenting with diabetic ketoacidosis (DKA) at the onset. In addition, all the FT1DM patients were followed up.

  Results  A total of 70 patients presenting with DKA at the onset of T1DM were admitted to and received treatment at West China Hospital in 2010–2019. Among them, 17 (24.3%) had FT1DM and 53 did not. The mean ages of the FT1DM patients and the non-FT1DM patients were (33.2±12.8) years and (27.5±11.2) years, and the mean body mass indices were (22.6±2.9) kg/m² and (19.2±2.9) kg/m², respectively. A total of 14 FT1DM cases had symptoms of upper respiratory tract infection or acute gastroenteritis before the onset of the disease and 4 cases were related to pregnancy. The median time from the onset of the disease to the first diagnosis of DKA of the FT1DM group (median P₂₅-P₇₅: 2 1-4 days, P<0.001) was significantly shorter than that of the non-FT1DM group (median P₂₅-P₇₅: 30 17-78 days). The mean maximum blood glucose levels at the time of the first visit to the doctor of the FT1DM patients (39.9±11.4 mmol/L, P<0.001) were significantly higher than that of the non-FT1DM patients (28.9±9.2 mmol/L), but the HbA1c (6.6%±0.6%, P<0.001) and glycosylated serum albumin (GA) (21.4%±3.0%, P=0.001) levels of the FT1DM patients were significantly lower than those of the non-FT1DM group (HbA1c: 12.8%±2.7%; GA: 44.8%±15.0%). The median serum amylase in the FT1DM group was significantly higher than that in the non-FT1DM group (101 54-336 IU/L vs. 54 42-166 IU/L, P=0.045) and the median serum lipase in the FT1DM group showed a trend of being higher than that in the T1DM group (81 57-154 IU/L vs. 46 28-195 IU/L, P=0.051). 8.7% of the non-FT1DM patients tested positive for anti-glutamic acid decarboxylase antibody (GAD-Ab), while the FT1DM patients all tested negative. At the time of discharge, the mean daily insulin dose of the FT1DM patients was (0.67±0.22) IU/kg, which was not significantly different from that of the non-FT1DM group (0.74±0.29 IU/kg, P=0.349). After about 6.5 years of follow-up, the mean daily insulin dose of the FT1DM patients was (0.73±0.19) IU/kg, which was similar to the insulin dosage on discharge (P=0.409).

  Conclusion  Compared with the non-FT1DM patients presenting with DKA at the onset, FT1DM patients have fewer typical diabetic symptoms, lower fasting C-peptide levels, higher serum amylase levels, and increased incidence of vomiting or other symptoms of gastrointestinal infections, and are more likely to be misdiagnosed. Therefore, it is very important for clinicians to correctly identify FT1DM as early as possible and administer early and long-term insulin replacement therapy.