. 2018 Mar 27;9(1):1–45. doi: 10.1007/s13340-018-0345-3

Table 6.

Gestational diabetes mellitus: its definition and diagnostic criteria

Definition	Gestational diabetes mellitus is defined as a state of pre-diabetic impaired glucose tolerance which is identified or which occurs for the first time during pregnancy and which does not include overt diabetes in pregnancy or pregnancy complicated by diabetes (pre-gestational diabetes mellitus)
Diagnostic criteria
Gestational diabetes mellitus	Individuals are to be diagnosed with gestational diabetes mellitus if they meet any of the following criteria in a 75 g oral glucose tolerance test (OGTT): ① Fasting glucose value: ≥ 92 mg/dL (5.1 mmol/L) ② 1-h post-OGTT glucose value: ≥ 180 mg/dL (10.0 mmol/L) ③ 2-h post-OGTT glucose value: ≥ 153 mg/dL (8.5 mmol/L)
Overt diabetes in pregnancy^a	Individuals are to be diagnosed with overt diabetes in pregnancy if they meet either of the following during pregnancy: ① Fasting glucose: ≥ 126 mg/dL (7.0 mmol/L) ② HbA1c: ≥ 6.5% * Individuals with casual glucose values of ≥ 200 mg/dL (11.1 mmol/L) or 2-h post-75 g OGTT glucose values of ≥ 200 mg/dL (11.1 mmol/L) in pregnancy are to be examined to see if they meet either ① or ② with the potential diagnosis of overt diabetes in pregnancy in mind^b
Pre-gestational diabetes mellitus	Individuals are to be diagnosed with pre-gestational diabetes mellitus if they meet either of the following: ① Diabetes mellitus diagnosed before pregnancy ② Pregnancy associated with unequivocal evidence of diabetic retinopathy

^aOvert diabetes mellitus in pregnancy includes diabetes mellitus overlooked before pregnancy, impaired glucose tolerance resulting from changes in glucose metabolism during pregnancy and type 1 diabetes mellitus occurring during pregnancy. In either case, the diagnosis needs to be confirmed in affected individuals after delivery

^bIndividuals are expected to show higher post-OGTT glucose values during pregnancy than usual, reflecting increased physiological insulin resistance during pregnancy, particularly in later stage. Thus, the casual glucose and post-75 g OGTT values defined in the diagnostic criteria for diabetes mellitus during non-pregnancy are not readily applicable (adapted from [11])