Aims To evaluate diagnostic strategy with OGTT and/or HbA1c for lowing number of people with undiagnosed T2DM.

Materiales and Methods Population-based screening for glucose metabolism impairments (GMI) among 661 adults in Moscow Country was conducted in 2009. HbA1c was determined in 39 subjects with GMI.

Results Based on OGTT and HbA1c, 6 and 11 people had T2DM; 33 and 23 people had prediabets. Mean HbA1c (SD) was 7.9 (2.8) for T2DM, 6.0 (0.5) for IGT and 5.8 (0.7) for IFG and 6.5 (0.5) for IGT+IFG. The sensitivity/specificity (Sn/Sp) of HbA1c >6.5 for T2DM were 66%/78%, Sn/Sp of HbA1c >5.7–6.4% for IGT were 68%/64%, for IFG were 50%/42% and for IGT+IFG were 50%/42%. Using Roc curve analysis, the single optimal HbA1c cut-point for detecting T2DM was >6.0%, (Sn/Sp: 50%/100%), for IFG was <5.0% (Sn/Sp: 50%/100%) in normal weight (BMI 18–25) individuals. RR of T2DM was 7 (1.18–42.9) with HbA1c values 6.0-6.4% and >6.5%, than those with <6.0 in normal weight individuals. 33.0% of undiagnosed T2DM had HbA1c levels <6.5% (95% CI 0% to 71%) and 17% of people with T2DM had HbA1c levels <6.0%.

Conclusion OGTT and HbA1c are both relevant diagnostic criteria for dysglycemia as they correlate with the risk for developing T2DM. Choosing the HbA1c strategy rather than the OGTT strategy leads to diagnose more diabetes, although the consistency of both diagnostic criteria is low. The optimal HbA1c cut-point to detect T2DM was lower than HbA1c of 6.5% in normal weight individuals.