Pre-diabetes is associated with an increased risk of cardiovascular disease, according to a new meta-analysis, with the risk seeming to rise at relatively low glucose levels, such as a fasting glucose concentration of 5.6mmol/L or HbA1c of 39mmol/mol.

The meta-analysis included 53 prospective studies involving about 1.6m people followed for a median of 9.5 years. The cut points for impaired fasting glucose and HbA1c for defining pre-diabetes differ between guidelines. Compared with people with normal glycaemia, prediabetes (defined by impaired glucose tolerance or impaired fasting glucose) was associated with a 13 to 30 per cent (depending on the criteria) increased risk of a composite of cardiovascular disease events.

Pre-diabetes increased the risk of coronary heart disease (by 10-20 per cent), stroke (6-20 per cent) and all-cause mortality (13-32 per cent). HbA1c between 39 and 47mmol/mol (5.7-6.4 per cent) was associated with a 21 and 15 per cent increased risk of the composite of cardiovascular events and coronary heart disease respectively.

An HbA1c of between 42 and 47mmol/mol (6.0-6.4 per cent) was associated with 25 and 28 per cent increased risk.

^{BMJ 2016; 355:i5953}