The increased risk of adverse cardiovascular outcomes associated with type 2 diabetes does not begin at the diagnostic cutoff for plasma glucose (or HbA1c) at which the condition is diagnosed. Rather, there appears to be a continuum of increased microvascular and macrovascular risk that extends to levels of glycemia well below these cutoffs.”
Hopper I, BillahB, Skiba M, Krum H. Prevention of diabetes and reduction in major cardiovascular events in studies of subjects with prediabetes: a meta-analysis of randomized controlled clinical trials. Eur J Cardiovasc PrevRehabil. 2011;18:813–823.