Update on pre-diabetes: Focus on diagnostic criteria and cardiovascular risk

Table 1 Diagnostic criteria for categories at increased risk of diabetes

Category	Marker	Diagnostic range
IFG	Fasting plasma glycemia	≥ 5.6 mmol/L (100 mg/dL)
		< 6.9 mmol/L (126 mg/dL)
IGT	2-h post-load glycemia	≥ 7.8 mmol/L (140 mg/dL)
		< 11 mmol/L (200 mg/dL)
HbA1c-prediabetes	HbA1c	≥ 39 mmol/mol (5.7%)
		< 47 mmol/mol (6.5%)

IFG: Impaired fasting glucose; IGT: Impaired glucose tolerance; HbA_1c: Glycated haemoglobin.

Table 2 Main points supporting/not supporting the use of glycated haemoglobin as diagnostic tool for diagnosis of pre-diabetes

Supporting	Not supporting
HbA1c may better integrate chronic hyperglycaemia than fasting and 2-h post-load glycaemia	HbA1c seems to have a lower sensitivity in pre-diabetes diagnosis
HbA1c predicts microvascular complications (rethinopathy and nephropathy) similarly to fasting and 2-h post-load glycaemia	Standardization of HbA1c assay needs to be improved
HbA1c has a higher predictive value than fasting plasma glucose in predicting cardiovascular disease HbA1c has a greater pre-analytical stability than blood glucose	Common, and not always known, clinical conditions (haemoglobinophaties, malaria, anaemia, blood loss) may significantly interfere with HbA1c assay
HbA1c assay does not need fasting status	Ethnic differences in HbA1c assay are not well characterized
HbA1c is not affected by acute perturbations (exercize, stress, diet) HbA1c biological variability is lower than fasting and 2-h post-load glycemia	The low biological variability of HbA1c provides little information on pathophysiological processes involved in pre-diabetes
HbA1c may be an attractive option in settings in which OGTT is not used and rarely repeated	Glucose assessment is cheaper thant HbA1c assay

HbA_1c: Glycated haemoglobin; OGTT: Oral glucose tolerance test.