HbA1c should be checked every three to six months for all people with type 2 diabetes. This should be more frequent at the beginning of a new treatment plan and extended to every six months when the HbA1c is stable at target and treatment is stable or unchanging. 

The International Federation of Clinical Chemistry (IFCC) system, which is measured in mmol/mol (millimoles per mole), has now replaced the Diabetes Control of Complications Trial (DCCT) percentage system of HbA1c measurement. Throughout this module, both measurements are presented, following the NICE guideline style. To convert these measurements, refer to the Diabetes UK converter tool. 

The target HbA1c is initially 48 mmol/mol (6.5 per cent) for all patients managed by diet and lifestyle modification. This target usually remains the same after starting oral blood glucose lowering medicines. However, if a medicine associated with hypoglycaemia is used (e.g. a sulfonylurea), the target is 53 mmol/mol (7.0 per cent).

A target of 53 mmol/mol may also be considered for adults taking a single blood glucose lowering medicine whose HbA1c rises to 58 mmol/mol (7.5 per cent) or higher. The NICE guideline recommends considering relaxing HbA1c targets on a case-by-case basis and suggests a number of triggers for discussing this option with patients, particularly for people who are older or frail, and where the risks of tight glycaemic control are likely to outweigh the potential benefits. 

Control of blood sugars can improve outcomes, but it is not without problems. Weight gain and increased risk of hypoglycaemia are two of the potential side effects with some medicines, so it is important to involve patients in decisions about their treatment options. Patients may want to consider what they are willing to undertake in order to reach their agreed targets and reduce the risk of long-term complications. 

Women who are trying to conceive are advised to maintain stricter control of blood sugars. This is increasingly important with the rise of type 2 diabetes in younger people and the risks associated with poor control during pregnancy. A pre-conception target of 48 mmol/mol (6.5 per cent) is recommended, and this should be maintained throughout pregnancy. Risks to both mother and child increase above 48 mmol/mol (6.5 per cent). Women with HbA1c greater than 86 mmol/mol (10 per cent) should be strongly advised not to get pregnant until their blood sugar is under control. You may need to stress the importance of effective contraception until blood sugar is stabilised, as well as the need for a higher dose of folic acid for pre-conception care.

These differing targets mean you will have to tailor your advice to each individual patient. The conversation may also differ depending on the patient’s age and treatment stage.