Early diagnosis of gestational diabetes mellitus by hba1c as a predictor - prospective Observational study

Abstract

Back ground Gestational diabetes mellitus (GDM) is characterized by glucose intolerance of any severity identified for the first time during pregnancy. The OGTT is the definitive test for identifying GDM. Various criteria adopt different values for the OGTT in the diagnosis of GDM. The OGTT, while the gold standard, is a complex procedure for subjects and healthcare practitioners. The participant must be fasting, necessitating a minimum of 2 hours for sample collection, during which at least two blood samples are obtained. The duration and quantity of samples obtained may increase based on the criteria employed. The WHO recognized HbA1C as a diagnostic instrument for diabetes mellitus in 2011. Still, no guidelines support the utilization of HbA1C as a diagnosis for GDM. This study was conducted to find the efficacy of HbA1c for early diagnosis of GDM. Methodology: The present study was done among 123 antenatal women with confirmed intrauterine pregnancy of gestational age. All the antenatal were sent for blood investigations. If the FBS exceeded 92 mg/dl or the HbA1c was below 6.5% during the first trimester, these values were deemed abnormal, prompting further evaluation in the second trimester with a repeat HbA1c and a 75 gm 2-hour DIPSI as a single- step protocol. All patients received 75 grams of anhydrous glucose dissolved in 250- 300 millilitres of water, and plasma glucose levels were measured after two hours. A number below 140 mg/dl was classified as normal, whereas a value beyond 200 mg/dl was diagnosed as overt diabetes. Any number ranging from 140 to 200 mg/dl was classified as impaired glucose tolerance. Patients with HbA1c levels below 6.5% and a DIPSI value ranging from 140 to 200 mg/dl underwent a 75g oral glucose tolerance test to validate the diagnosis of GDM. Results: Most cases (57.7%) were 21-25 years, followed by 26-30 years (26.8%). Multi-para was seen in 62.6% of cases. Overweight was seen in 15.4% of cases, and obesity was seen in 43.1% of cases. Vaginal delivery was seen in 65% of cases, and 2.4% of cases had pre-term deliveries. Low birth weight was seen in 3.3% of cases, and NICU admission was 28.5%. Of the total cases, 13.8% of cases were diagnosed as diabetic. Regarding diagnosing GDM, HBA1C had a sensitivity of 94.1%, specificity of 86.5%, PPV of 98.1% and NPV of 85.2%, with 5.65 as a cut-off level of HBA1C to diagnose as diabetic. Conclusion: HbA1C is considered as a reliable test for diagnosing GDM by WHO, which can help identify at-risk mothers so that care can be provided for a better outcome. GDM cases were counselled and advised regarding dietary as well as life style modification, which helped to reduce the complications in the latter half of pregnancy.