A Chinese research group analyzed 53 studies and found an association between prediabetes and increased cardiovascular disease and mortality risk, even when prediabetes was defined based on lower glucose cut-off values.
Prediabetes is the state between normal glucose metabolism and diabetes, with either impaired fasting glucose (IFG) or impaired glucose tolerance (IGT: glucose is too high 2 hours after eating). However, different guidelines use different glucose and HbA1c (a molecule that is associated with impaired glucose metabolism) cut-off values to determine prediabetes, so the definition of prediabetes is still not clear. Also, some argue, that the lower cut-off glucose values might not mean a higher cardiovascular or mortality risk, therefore, they might be unnecessary.
A study group published their meta-analysis in the British Medical Journal that investigated the association between prediabetes and the risk of cardiovascular disease. They included 53 studies in their analysis with 1,611,339 participants. The median duration of follow-up was 9.5 years. Both IGT and IFG were associated with an increased risk of mortality, and the relative risk did not differ between different guidelines (and cut-off values). However, mortality risk was not increased when prediabetes was diagnosed based on HbA1c measurements. The increased risk of mortality was significantly higher in the IGT group than in any other prediabetes groups. Furthermore, the analysis found an increased risk of both cardiovascular disease and coronary heart disease in all prediabetes groups. The relative risk did not differ significantly between the different prediabetes definition groups and it was independent from smoking. Authors also found an association between prediabetes and increased stroke risk, but only when prediabetes was diagnosed based on either IGT or IFG, but not HbA1c.
In conclusion, authors found an increased cardiovascular and mortality risk in prediabetes, even at lower cut-off fasting glucose values, and this may support the use of lower cut-off points and the incorporation of HbA1c in defining prediabetes.
Written By: Dr. Fanni R. Eros