A 5-year Follow-up of Subjects with Fasting Plasma Glucose Above 5.6 mmol/l Found in a Screening Study of the Bulgarian Population

Abstract

The WHO and many other diabetes organizations recommend performing OGTT at fasting plasma glucose ≥ 6.1 ÷ 6.9 mmol/L mmol/L, but ADA indicates a lower cut-off for this parameter - ≥ 5.6 ÷ 6.0 mmol/L mmol/L. <i>Aim:</i> We decided to evaluate the role of baseline glucose tolerance for the development of Diabetes or Prediabetes over time by a prospective study of the changes in glucose tolerance 5 years after the last nationwide cross-sectional study in Bulgaria. <i>Material:</i> The study included 204 subjects from a total of 2033 tested 5 years ago. These 204 individuals were selected among those with a fasting plasma glucose (FPG) 6.1 – 6.9 mmol/L (Group 1) and FPG ≥ 5.6 ÷ 6.0 mmol/L (Group 2) found during the screening in 2012. As a part of the screening in 2017, a standard OGTT was performed (WHO’1999) and HbA1c was determined. <i>Methods:</i> Plasma glucose was measured in all the studies by an automated glucose-oxidase analyzer (Glucose Analyzer II, Beckman Coulter, Inc). HbA1c was determined by immunoturbidimetric method after hemolysis of a whole blood sample. <i>Results:</i> Half of the subjects with FPG 6.1 - 6.9 mmol/L in 2012 had Diabetes during the follow up, 31% remained in the Prediabetes group and 19% had Normal glucose tolerance (NGT) in 2017. Among the subjects with FPG ≥ 5.6 - 6.0 mmol/L in 2012, 24.7% had Diabetes in 2017, 34.6% - Prediabetes and 40.7% had NGT. The difference in the Diabetes prevalence between the two groups was significant – 50% vs. 24.7% (T=2.443, P < 0.02). In 5 years’time, 29.9% of the Individuals who had FPG ≥ 5.6 - 6.9 mmol/L in 2012, became Diabetics, 33.6% became Prediabetics and only 36.3% had NGT. In 57% (35/61) of the diabetics the disease was newly diagnosed and in about 2/3 of the cases it was decompensated (HbA1c ≥ 7%). During the 5-year period, Diabetes was diagnosed in 26 (42.6%) persons and 34.6% of them were in metabolic decompensation under treatment. <i>Conclusion:</i> The most important conclusion from our screening from 2017 is that ¼ people with FPG ≥ 5.6 – 6.0 mmol/L after a few years became diabetics, so systematic efforts should be directed towards this border group.