Table 3.

Diagnostic criteria (2023) of slowly progressive type 1 diabetes (SPIDDM).

Required Item:

(1) The presence of anti-islet autoantibodies at some time point during the disease course a;

(2) The absence of ketosis or ketoacidosis at the diagnosis of diabetes and the unnecessity for insulin treatment to correct hyperglycemia immediately after diagnosis in principle;

(3) The gradual decrease in insulin secretion overtime, requirement of insulin treatment more than 3 months b after diagnosis of diabetes, and exhausted endogenous insulin secretion (fasting serum C-peptide immunoreactivity < 0.6 ng/mL) at last observed time point.

Judgement:

When the case fulfills the criteria of all of the three described above ((1), (2), and (3)), the case is diagnosed with “slowly progressive type 1 diabetes (definite)”; when the case fulfills the criteria only (1) and (2), but not (3), the case is diagnosed with “slowly progressive type 1 diabetes (probable)”.

^a Anti-islet autoantibodies include glutamic acid decarboxylase (GAD) autoantibody, insulinoma-associated antigen-2 (IA-2) autoantibody, islet cell antibody (ICA), zinc transporter 8 (ZnT8) autoantibody or insulin autoantibody (IAA). The measurement of IAA should be performed before starting insulin treatment. ^b More than 6 months in a typical case.