Diabetes mellitus is the group of serious diseases that lead to fatal cases without the proper treatment. One of the suggested by the World Health Organization, the International Expert Committee, and the American Diabetes Association ways of diagnostics of diabetes is the measure of the glycated hemoglobin level (HbA1c); HbA1c more than 6,5% (48 mmol/mol) diagnoses diabetes, and HbA1c between 5,7% and 6,4% diagnoses prediabetes (Incani et al., 2015, p. 44). However, this method needs to be improved and additional factors need to be studied, as the level of HbA1c shows poor agreement with fasting plasma glucose (FPG) and 2-h plasma glucose (2 hPG). Incani et al. study the impact of the obesity level on HbA1c and discuss the influence of phenotypes on the differences between HbA1c and blood glucose levels.
Incani et al. selected 1,054 Caucasian participants; 592 of them were from the obesity clinic, and the other 462 were from the diabetic screening clinic. The age of the first cohort was 45.8 ± 13.1, and the age of the second one was 52.8 ± 15.1. The level of HbA1c was measured with the use of a G8 analyzer, and the concentration of serum glucose was measured with a Miura 200 Chemistry analyzer using an automated enzymatic ultraviolet method, glucose-6-phosphate dehydrogenase/hexokinase. All participants were diagnosed with the type 2 diabetes on the basis of FPG ≥ 7.0 mmol/L or 2 hPG ≥ 11.1 mmol/L after the 75-g OGTT. Prediabetes was diagnosed on the basis of FPG ≥ 5.6 mmol/L or 2 hPG ≥ 7.8-11.05 mmol/L after the 75-g OGTT (Incani et al., 2015, p. 45). Incani et al. also recorded lipid parameters, blood pressure and BMI of each participant after the OGGT, 0 min insulin level, and 2 h insulin level.
The results of the study showed a significant difference between two cohorts of participants. Obesity clinic patients demonstrated a good correlation between the level of HbA1c and diabetes: 69,3% of them had HbA1c more than 6,5% with diabetes determined by OGTT (Cohen’s kappa 0.666). However, the agreement between prediabetes and the level of HbA1c was poor: only 38.2% of the participants with Cohen’s kappa 0.202. At the same time, diabetic screening clinic patients demonstrated the fair agreement between diabetes and the level of HbA1c (Cohen’s kappa 0.317) and the poor agreement between HbA1c and prediabetes (Cohen’s kappa 0.187). Incani et al. revealed that the agreement between diabetes and the level of HbA1c was much higher among the patients with class I obesity (Incani et al., 2015, p. 47). They studied the phenotype characteristics of the participants with the different results of HbA1c and OGTT and concluded that age and male sex were crucial for the choice of the diagnostic method. Incani et al. recommended using OGTT for the diagnosis of diabetes in people younger than 55 years, while for males above this age one could choose HbA1c.
While it still might be difficult to determine diabetes or prediabetes just on the basis of one diagnostic method, the findings of Incani et al. help in choosing the more accurate one for the diagnosis of diabetes among males above 55 years old with the I class obesity. The study was the first to show the positive correlation between the class of obesity and the results of the HbA1c diagnostic test. Thus, when the patient is a male above 55 years old, before choosing the diagnosis method, one should check his BMI and determine the obesity class. If the patient has the I class obesity, it will be better to choose HbA1c, as it is cost-effective and demonstrates high performance; 80% of the participants of the study with the I class obesity had diabetes both by HbA1c test and OGTT test (Incani et al., 2015, p. 47). The integration of the findings into the modern practice of diagnosis of diabetes is the easier way of choosing the diagnosis test and the high probability of the credibility of the HbA1c test results for the mentioned group of the patients. The study correlates with the findings of the other specialists in the sphere of HbA1c; thus, the probability of making the mistake the necessity of conducting the other test reduces, which increases cost-efficiency (Incani et al., 2015, p. 49).
References
Incani, M., Sentinelli, F., Perra, L., Pani, M. G., Porcu, M., Lenzi, A., Cavallo, M. G., Cossu, E., Leonetti, F., & Baroni, M. G. (2015). Glycated hemoglobin for the diagnosis of diabetes and prediabetes: Diagnostic impact on obese and lean subjects, and phenotypic characterization. Journal of Diabetes Investigation, 6, 44-50. Retrieved from https://pdfs.semanticscholar.org/a4ad/39811c9c5b1f3af3c05e420b1f6b97c2b622.pdf.
