reference range (glycosylated haemoglobin)

Last reviewed 08/2021

For diabetics:

• HbA1c levels of between 6.5% and 7.5% are recommended by NICE (1)
  • a MeREC review (2) states that "..If appropriate and achievable in an individual, reducing blood glucose to HbA1c levels of around 7.5% would seem optimal based on current evidence. Lower levels may be appropriate for individuals with early disease..."

• NICE note that for type 2 diabetes (1):
  • for adults with type 2 diabetes managed either by lifestyle and diet, or by lifestyle and diet combined with a single drug not associated with hypoglycaemia, support the person to aim for an HbA1c level of 48 mmol/mol (6.5%)
    • for adults on a drug associated with hypoglycaemia, support the person to aim for an HbA1c level of 53mmol/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 53mmol/mol (7.0%)
    • and intensify drug treatment
      
      
  • consider relaxing the target HbA1c level on a case-by-case basis, with particular consideration for people who are older or frail, for adults with type 2 diabetes:
    • who are unlikely to achieve longer-term risk-reduction benefits, for example, people with a reduced life expectancy
    • for whom tight blood glucose control poses a high risk of the consequences of hypoglycaemia, for example, people who are at risk of falling, people who have impaired awareness of hypoglycaemia, and people who drive or operate machinery as part of their job
    • for whom intensive management would not be appropriate, for example, people with significant comorbidities
      
      
  • If adults with type 2 diabetes achieve 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
    
    
  • HbA1c lower than target:
    • if adults with type 2 diabetes achieve 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
      
      
  • 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 note for type 1 diabetes (3):
  • 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, taking into account factors such as the person's 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

Notes:

• JBS2 suggest an optimal target for glycaemic control in diabetes is a fasting or pre-prandial glucose value of 4.0-6.0 mmol/l and a HbA1c < 6.5%. An audit standard for HbAlc of <7.5% is recommended
• the HbA1c results will be reported exclusively as mmol/mol of haemoglobin without glucose attached, rather than a percentage as previously, from June 1st 2011
• the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) has initiated the change:
• the equivalent of the current DCCT HbA1c targets of 6.5% and 7.5% are 48 mmol/mol and 59 mmol/mol in the new units, with the nondiabetic reference range of 4.0% to 6.0% being 20 mmol/mol to 42 mmol/mol

• %	4.0	4.1	4.2	4.3	4.4	4.5	4.6	4.7	4.8.	4.9
  mmol/mol	20	21	22	23	25	26	27	28	29	30
  %	5.0	5.1	5.2	5.3	5.4	5.5	5.6	5.7	5.8	5.9
  mmol/mol	31	32	33	34	36	37	38	39	40	41
  %	6.0	6.1	6.2	6.3	6.4	6.5	6.6	6.7	6.8	6.9
  mmol/mol	42	43	44	45	46	48	49	50	51	52
  %	7.0	7.1	7.2	7.3	7.4	7.5	7.6	7.7	7.8	7.9
  mmol/mol	53	54	55	56	57	58	60	61	62	63
  %	8.0	8.1	8.2	8.3	8.4	8.5	8.6	8.7	8.8	8.9
  mmol/mol	64	65	66	67	68	69	70	72	73	74
  %	9.0	9.1	9.2	9.3	9.4	9.5	9.6	9.7	9.8	9.9
  mmol/mol	75	76	77	78	79	80	81	83	84	85
  %	10.0	10.1	10.2	10.3	10.4	10.5	10.6	10.7	10.8	10.9
  mmol/mol	86	87	88	89	90	91	92	93	95	96
  %	11.0	11.1	11.2	11.3	11.4	11.5	11.6	11.7	11.8	11.9
  mmol/mol	97	98	99	100	101	102	103	104	105	107
  %	12.0	12.1	12.2	12.3	12.4	12.5	12.6	12.7	12.8	12.9
  mmol/mol	108	109	110	111	112	113	114	115	116	117
  %	13.0	13.1	13.2	13.3	13.4	13.5	13.6	13.7	13.8	13.9
  mmol/mol	119	120	121	122	123	124	125	126	127	128

Reference:

1. NICE (December 2015).Type 2 diabetes The management of type 2 diabetes
2. MeReC Bulletin June 2011; 21 (5)
3. NICE (August 2015). Type 1 diabetes in adults: diagnosis and management