Low concordance between HbA1c and OGTT to diagnose prediabetes and diabetes in overweight or obesity

Abstract

Background Glycated haemoglobin (HbA1c) test, introduced for diagnosing prediabetes and diabetes by the American Diabetes Association for some years, is currently under extensive discussion for contradictory data on the concordance between this test and the oral glucose tolerance test (OGTT). Hypothesis To assess concordance between HbA1c and OGTT to diagnose prediabetes and diabetes in subjects with overweight or obesity, focusing on possible gender‐related differences. Methods A total of 949 outpatients with overweight or obesity at risk for diabetes (mean age 50 ± 15 years; 660 F) were enrolled and underwent HbA1c test and OGTT. Results In both genders, HbA1c test identified more patients with prediabetes than OGTT (42% vs 22% in males, 40% vs 18% in females, respectively): a slight concordance between HbA1c and OGTT (60% of total tests in both genders). In subjects diagnosed by OGTT, post‐OGTT insulin levels and HOMA INDEX were significantly higher than those found in HbA1c(+) cases. Instead, those diagnosed with HbA1c were significantly older and showed higher uric acid than those with both tests (−). Conclusions HbA1c test and OGTT did not reach full concordance for the diagnosis of diabetes and prediabetes in both genders. The two tests likely reflect different physiopathological aspects of dysglycaemia, suggesting that the ‘diagnostic thresholds’ could be reconsidered in light of the discordance observed.

Diagnostic criteria for the diagnosis of type 2 diabetes: Discordance of multiple measures

“…A 15‐year follow‐up demonstrated a persistence of this effect and an overall 28% reduction in microvascular complications . The data presented in Chatzianagnostou et al demonstrate the lack of sensitivity for the diagnosis of T2D in those at greatest risk. On the one hand, pharmacologic treatment with an oral, generic hypoglycaemic agent like metformin can have a potential very positive effects on mortality and quality of life.…”

“…This paper highlights the potential problems of using two very different diagnostic criteria for a medical diagnosis that will result in a pharmacological therapy to improve glycaemic control that results from the complex nature of the aetiology of impaired glucose tolerance and type 2 diabetes. In the population tested in this study, none of the subjects had a previous diagnosis of IGT or T2D yet a substantial number had some degree of impaired glycaemic control. The specific diagnostic criteria for T2D have been well described and approved by both regulatory and drug reimbursement groups throughout the world.…”

“…The report of Chatzianagnostou et al reminds us that insulin resistance and type 2 diabetes (T2D) have a highly complex aetiology that involves long‐term adaptations of multiple tissues. Multiple mediators of hepatic and skeletal muscle insulin action including adipokines, cytokines, diet, physical activity and inactivity, chronic diseases, and obesity have been described.…”

“…However, the degree of discordance in diagnosis in a population at risk in the report of Chatzianagnostou et al is a cause of some concern. This paper highlights the potential problems of using two very different diagnostic criteria for a medical diagnosis that will result in a pharmacological therapy to improve glycaemic control that results from the complex nature of the aetiology of impaired glucose tolerance and type 2 diabetes.…”

“…However, a strong recommendation should be made to regulators and, in particular third‐party payers, to consider impaired glucose tolerance and T2D as a continuum with no specific threshold for use and reimbursement for drugs that can improve glycaemic control and decrease the risk of morbidity and mortality. The data in Chatzianagnostou et al reveal the lack of specificity and sensitivity of these diagnostic tests among those at highest risk for T2D and because of this, the decision for a pharmacological treatment plan for any patient should not be determined using a binary test result. A physician should be able to provide a patient with poor glycaemic control and evidence of insulin resistance the best possible therapy even without a specific diagnosis of T2D.…”