NICE guidance - HbA1c

NICE notes that for type 2 diabetes (1):

• for adults whose type 2 diabetes is managed either by lifestyle and diet, or lifestyle and diet combined with a single drug not associated with hypoglycaemia, support them to aim for an HbA1c level of 48 mmol/mol (6.5%)
• for adults on a drug associated with hypoglycaemia, support them to aim for an HbA1c level of 53 mmol/mol (7.0%)
• in adults with type 2 diabetes, if HbA1c levels are not adequately controlled by a single drug and rise to 58 mmol/mol (7.5%) or higher:
  • reinforce advice about diet, lifestyle and adherence to drug treatment and
  • support the person to aim for an HbA1c level of 53 mmol/mol (7.0%) and
  • intensify drug treatment
• consider relaxing the target HbA1c level on a case-by-case basis and in discussion with adults with type 2 diabetes, with particular consideration for people who are older or frailer, if:
  • they are unlikely to achieve longer-term risk-reduction benefits, for example, people with a reduced life expectancy
  • tight blood glucose control would put them at high risk if they developed hypoglycaemia, for example, if they are at risk of falling, they have impaired awareness of hypoglycaemia, or they drive or operate machinery as part of their job
  • intensive management would not be appropriate, for example if they have significant comorbidities
• if adults with type 2 diabetes reach an HbA1c level that is lower than their target and they are not experiencing hypoglycaemia, encourage them to maintain it. Be aware that there are other possible reasons for a low HbA1c level, for example deteriorating renal function or sudden weight loss
• for guidance on HbA1c targets for women with type 2 diabetes who are pregnant or planning to become pregnant, see the NICE guideline on diabetes in pregnancy
• measure the individual's HbA1c levels at:
  • 3-6-monthly intervals (tailored to individual needs) until the blood glucose level is stable on unchanging therapy
  • 6-monthly intervals once the blood glucose level and blood glucose-lowering therapy are stable
    

NICE notes for type 1 diabetes (2):

• support adults with type 1 diabetes to aim for a target HbA1c level of 48 mmol/mol (6.5%) or lower, to minimise the risk of long-term vascular complications
• agree an individualised HbA1c target with each adult with type 1 diabetes. Take into account factors such as their daily activities, aspirations, likelihood of complications, comorbidities, occupation and history of hypoglycaemia
• ensure that aiming for an HbA1c target is not accompanied by problematic hypoglycaemia in adults with type 1 diabetes
• diabetes services should document the proportion of adults with type 1 diabetes who reach an HbA1c level of 53 mmol/mol (7%) or lowers
• measure HbA1c levels every 3-6months in adults with type 1 diabetes
• consider measuring HbA1c levels more often in adults with type 1 diabetes if the person's blood glucose control is suspected to be changing rapidly; for example, if the HbA1c level has risen unexpectedly above a previously sustained target

Notes:

• If HbA1c monitoring is invalid because of disturbed erythrocyte turnover or abnormal haemoglobin type, estimate trends in blood glucose control using one of the following:
  • fructosamine estimation
  • quality-controlled blood glucose profiles
  • total glycated haemoglobin estimation (if abnormal haemoglobins)
    
    

Reference:

1. NICE (August 2022).Type 2 diabetes The management of type 2 diabetes
2. NICE (August 2022). Type 1 diabetes in adults: diagnosis and management