Is there a role for glycated albumin in the diagnosis of gestational diabetes mellitus?

BACKGROUND: Studies in the general population have advocated glycated albumin (GA) as a useful alternative to glycated haemoglobin (HbA1c) under conditions wherein the latter does not reflect glycaemic status accurately. There are few studies in other populations, especially in pregnant women. Therefore, the aim of this study was to assess the clinical utility of GA in the diagnosis of gestational diabetes mellitus (GDM). MATERIALS AND METHODS: This diagnostic test accuracy study was performed in 149 Brazilian women at 24-28 weeks of gestation referred for an oral glucose tolerance test (OGTT) in a tertiary university hospital. Receiver Operating Characteristic (ROC) curves were used to access the performance of GA and HbA1c in the diagnosis of GDM by the reference OGTT. RESULTS: GDM by OGTT (IADPSG criteria) was detected in 18.8% of participants. According to ROC analysis, the area under the curve (AUC) for GA was 0.531 (95% CI: 0.405-0.658, p = 0.065) lower than that for HbA1c [0.743 (95% CI: 0.636-0.849; p ≤ 0.001] for the detection of GDM (p = 0.004). The equilibrium cut-off value for GA was 12.6%; sensitivity and specificity in this cut-off point were 53.6% and 54.2%, respectively. CONCLUSIONS: GA at 24-28 weeks of gestation does not have ability to correctly discriminate those with and without GDM. In summary, the lack of sensitivity found in our results do not support the solely use of GA in the diagnosis of GDM.

Effect of iron supplementation on HbA1c levels in pregnant women with and without anaemia.

BACKGROUND: Iron deficiency anaemia has been associated with higher HbA1c levels. However, during and after iron supplementation there is a decrease in HbA1c results, causing a misinterpretation. Our aim was to analyse the effect of iron supplementation on HbA1c levels in nondiabetic pregnant women with and without anaemia. METHODS: Pregnant women in prenatal care, without gestational diabetes (GDM) or previous diabetes mellitus (DM) that performed an oral glucose tolerance test (OGTT) in the third trimester of pregnancy were invited to participate. Clinical and laboratorial analyses were performed, including standardized questionnaire, OGTT, full blood count and HbA1c. RESULTS: A total of 231 pregnant women without DM or GDM were included in the study. According to anaemia and/or iron supplementation, we divided women in: no iron and no anaemia - Group 1 (N=86); no iron and with anaemia - Group 2 (N=29); iron and no anaemia - Group 3 (N=87); iron and anaemia - Group 4 (N=29). There was statistically a significant, although no clinically relevant, difference between HbA1c values in pregnant women in Groups 1 and 4 [5.1±0.4% (32±4.4mmol/mol) and 4.8±0.3% (29±3.3mmol/mol), P<0.01; respectively]. HbA1c values in pregnant women in Groups 1, 2 and 3 were similar, independently of anaemia [5.1±0.4% (32±4.4mmol/mol); 5.0±0.4% (31±4.4mmol/mol) and 5.0±0.4% (31±4.4mmol/mol); p>0.05; respectively]. CONCLUSIONS: Iron supplementation during pregnancy does not affect HbA1c levels and has no clinical impact in the final interpretation of results in the absence of anaemia or presence of mild anaemia. Interpreting HbA1c results in pregnant women during iron therapy and with moderate or severe anaemia still requires caution.

HbA1c Test as a Tool in the Diagnosis of Gestational Diabetes Mellitus.

AIMS: Gestational diabetes mellitus (GDM) is a prevalent and potentially serious condition which may put both mothers and neonates at risk. The current recommendation for diagnosis is the oral glucose tolerance test (OGTT). This study aimed to determine the usefulness of HbA1c test as a diagnostic tool for GDM as compared to the traditional criteria based on the OGTT. METHODS: This was a diagnostic test accuracy study. We performed OGTT and HbA1c test in women attending prenatal visits at a tertiary hospital. GDM was defined according to WHO1999 or ADA/WHO 2013 criteria. ROC curve was used to evaluate the diagnostic performance of HbA1c. Sensitivity, specificity and likelihood ratios for different HbA1c cut-off points were calculated. RESULTS: Of the 262 women in the third trimester of gestation enrolled in the study, 86 (33%) were diagnosed with GDM. Only five of these women presented HbA1c ≥48 mmol/mol (6.5%). This cut-off point presented 100% specificity but very low sensitivity (7%). Based on ROC curve, and considering OGTT as the reference criterion, HbA1c ≥40 mmol/mol (5.8%) showed adequate specificity in diagnosing GDM (94.9%) but low sensitivity (26.4%). Unlike, HbA1c values of 31 mmol/mol (5.0%) presented adequate sensitivity (89.7%) but low specificity (32.6%) to detect GDM. For women with HbA1c ≥40 mmol/mol (5.8%), the positive and negative likelihood ratios were 5.14 (95%CI 2.49-10.63) and 0.78 (0.68-0.88), respectively. The post-test probability of GDM was about 40%, representing a 4.0-fold increase in the mean pre-test probability. This cut-off point could eliminate the need for the unpleasant and laborious OGTT tests in almost one third of cases, as 38% of patients with GDM may be diagnosable by HbA1c test alone. CONCLUSIONS: Our results show that combined HbA1c and OGTT measurements may be useful in diagnosing GDM.