ABSTRACT
The Royal College of Obstetrics and Gynaecology advocated replacing OGTT with HbA1c for gestational diabetes (GDM) screening for women with risk factors during the Covid-19 pandemic. HbA1c >=48mmol/mol/random plasma glucose (RPG) >=11.1mmol/l at booking indicated diabetes, and 41-47mmol/ mol/9-11mmol/ l prediabetes or possible GDM. Testing was repeated at 26 weeks if normal previously, with HbA1c >=39mmol/mol, fasting PG >=5.6mmol/l, or RPG >=9mmol/l diagnostic for GDM. A) At her clinic booking visit at 10 weeks gestation, 36 year-old South Asian female had HbA1c 55mmol/mol/RPG 9.5mmol/l suggesting undiagnosed type 2 diabetes. Initially managed with dietary advice and home blood glucose monitoring, metformin was added when self-monitored glucose above pregnancy targets (fasting and pre-meal <5.3mmol/l or 1 h post meal <7.8mmol/l) but insulin was required later. Metformin and insulin were stopped after delivery at 38 weeks with HbA1c 50mmol/mol three months postpartum, supporting the earlier diagnosis of type 2 diabetes. B) 32 year-old White Caucasian female was screened for GDM on booking at 11 weeks as BMI 38 kg/m2. HbA1c 44mmol/mol and RPG 6.9mmol/l confirmed GDM which was managed by dietary/lifestyle changes with glucose and pregnancy targets achieved until 28 weeks when metformin added. Normal delivery at 40 weeks with HbA1c 40mmol/mol three months postpartum triggered advice on long-term dietary/lifestyle changes and annual HbA1c checks. HbA1c was useful during the pandemic but most centres reverted to OGTT for GDM screening due to a significant fall in diagnoses using HbA1c >=39mmol/mol at 26 weeks. But, HbA1c testing was advantageous at booking to diagnose type 2 diabetes earlier.
ABSTRACT
HbA1c measurement is widely used for diagnosis/ management/remission of diabetes with international schemes certifying comparability. A) 75 year-old Chinese female with type 2 diabetes was admitted in April 2020 with Covid-19 and diabetic ketoacidosis. Glucose was 35mmol/l and HbA1c 150mmol/mol with previous HbA1c of 45mmol/mol on metformin and alogliptin. She was treated for ketoacidosis and once-daily Lantus introduced along with supportive management of viral illness. B) 68 year-old Afro-Caribbean with type 2 diabetes on metformin before admission, presented with new onset, jerky ballistic movements of high amplitude in right arm, 10-15 movements every 5 min. Admission glucose was >33mmol/l, ketones 1.8mmol/l and HbA1c >217mmol/ mol. Hemichorea-hemiballism, a hyperglycaemia related movement was diagnosed and insulin commenced. Glucose decreased to 8-20mmol/ l, reaching 5-15mmol/ l by time of discharge. Ballistic movements resolved when glycaemic control improved with HbA1c 169mmol/mol, 25 days after discharge. C) Several days before admission, a female with diabetes over 20 years required attention from paramedics on four occasions for hypoglycaemia. Months beforehand metformin was replaced by gliclazide due to chronic kidney disease with HbA1c 50mmol/mol, and she was transfused six weeks before admission for microcytic anaemia. Gliclazide was discontinued and her diet modified which prevented further hypoglycaemic episodes. Variant haemoglobin, beta-thalassaemia which can overestimate glycaemia;undetected by HbA1c HPLC method, invalidated HbA1c as did the blood transfusion. These cases highlight that inadequate understanding of HbA1c can lead to acute presentations of dysglycaemia. As HbA1c accuracy can be affected by multiple factors, clinical assessment and triangulation are key to the management of such patients.