Barriers in HbA1c targets remain a significant challenge in UK diabetes care, preventing many people from achieving the glycaemic control needed to reduce long-term complications. HbA1c — a measure of average blood glucose over two to three months — is central to diabetes management, with NICE recommending individualised targets for both type 1 and type 2 diabetes. Yet National Diabetes Audit data consistently show that a substantial proportion of patients remain above recommended thresholds. Understanding the clinical, patient-related, socioeconomic, and systemic factors that hinder target achievement is essential for clinicians and patients alike in improving outcomes across the UK.

Understanding HbA1c Targets in UK Diabetes Care

NICE recommends individualised HbA1c targets — typically 48 mmol/mol for most adults and 53 mmol/mol where hypoglycaemia risk exists — though a significant proportion of UK patients do not consistently meet these thresholds.

HbA1c (glycated haemoglobin) is the cornerstone measure of long-term glycaemic control in people living with diabetes. It reflects average blood glucose levels over the preceding two to three months and is expressed in mmol/mol under the IFCC standardisation adopted across the UK. Regular monitoring of HbA1c is central to diabetes management, as sustained elevated levels are strongly associated with microvascular and macrovascular complications, including retinopathy, nephropathy, neuropathy, and cardiovascular disease.

NICE guidelines recommend individualised HbA1c targets rather than a one-size-fits-all approach. For most adults with type 2 diabetes managed with lifestyle measures or a single non-hypoglycaemic drug, a target of 48 mmol/mol (6.5%) is advised (NICE NG28). Where additional medications are used, or where hypoglycaemia risk is a concern, the target is typically relaxed to 53 mmol/mol (7.0%). For adults with type 1 diabetes, NICE NG17 recommends aiming for 48 mmol/mol where safely achievable, acknowledging that tighter control must be balanced against hypoglycaemia risk. Higher targets are appropriate in people with frailty, significant comorbidity, limited life expectancy, or a history of recurrent hypoglycaemia — reflecting the importance of personalised goal-setting.

It is important to note that HbA1c has recognised limitations as a measure. Results may be unreliable in pregnancy, in people with haemoglobin variants (such as HbS or HbC, more prevalent in some ethnic groups), significant anaemia, chronic kidney disease affecting red cell turnover, or following a recent blood transfusion. In these circumstances, capillary blood glucose monitoring or continuous glucose monitoring (CGM) data should guide clinical decisions.

Despite clear guidance, a significant proportion of people with diabetes in the UK do not consistently meet their HbA1c targets. National Diabetes Audit (NDA) data consistently highlight that a substantial number of patients remain above recommended thresholds. Understanding the barriers in HbA1c targets — whether clinical, behavioural, or systemic — is therefore essential for improving outcomes and reducing the long-term burden of diabetes-related complications across the population.

Common Clinical Barriers to Achieving HbA1c Goals

Therapeutic inertia, medication side effects, and comorbidities such as chronic kidney disease are the primary clinical barriers that delay or prevent HbA1c target achievement.

From a clinical perspective, several pharmacological and physiological factors can impede the achievement of HbA1c targets. One of the most significant is therapeutic inertia — the failure of clinicians to intensify treatment in a timely manner when glycaemic control is suboptimal. Studies suggest that delays of months or even years can occur between identifying poor control and adjusting therapy, contributing meaningfully to prolonged hyperglycaemia.

The complexity of diabetes pharmacotherapy also presents challenges. Many patients require multiple agents to achieve adequate control, and the side-effect profiles of certain medications can limit adherence or dose escalation. For example:

• Metformin may cause gastrointestinal intolerance, particularly at higher doses; slow titration or switching to a modified-release formulation can improve tolerability. Per MHRA guidance and individual SmPCs, the dose should be reviewed if eGFR falls to 30–45 ml/min/1.73m², and metformin is contraindicated when eGFR is below 30 ml/min/1.73m²

• Sulphonylureas carry a risk of hypoglycaemia, which can make patients and clinicians reluctant to optimise dosing

• Insulin therapy is associated with weight gain and hypoglycaemia, and its initiation is often delayed due to both patient reluctance and clinical caution

Comorbidities further complicate glycaemic management. Conditions such as chronic kidney disease (CKD) restrict the use of certain agents. For SGLT-2 inhibitors, the renal threshold for glucose-lowering efficacy is agent-specific — generally, glycaemic benefit diminishes at lower eGFR levels and most agents are not recommended for glucose lowering below eGFR 45 ml/min/1.73m²; however, some agents retain a licence for use at lower eGFR thresholds when prescribed for heart failure or CKD-related cardioprotection, in line with NICE technology appraisals and individual SmPCs. Clinicians should consult the relevant SmPC and NICE guidance (including NG28 and UK Kidney Association recommendations) for agent-specific and indication-specific thresholds. Similarly, recurrent infections, corticosteroid use, or intercurrent illness can cause transient but significant HbA1c elevations that are difficult to manage within standard review cycles.

If you experience unexpected or troublesome side effects from any diabetes medication, these should be reported to the MHRA via the Yellow Card scheme at yellowcard.mhra.gov.uk or using the Yellow Card app. Recognising these clinical barriers is the first step towards addressing them systematically.

Patient-Related Factors That Affect Glycaemic Control

Medication non-adherence, low health literacy, poor diet, physical inactivity, and psychological difficulties such as diabetes distress and depression are key patient-related barriers to glycaemic control.

Patient-related factors represent some of the most complex and multifaceted barriers in HbA1c targets. Medication non-adherence is among the most prevalent, with evidence suggesting that a substantial proportion of people with long-term conditions do not take their medicines as prescribed. Reasons are varied and include forgetfulness, pill burden, fear of side effects, and a lack of perceived benefit — particularly in the early stages of diabetes when symptoms may be absent.

Health literacy plays a critical role. Patients who do not fully understand the relationship between blood glucose, HbA1c, and long-term complications may not appreciate the importance of consistent medication use or dietary modification. This is compounded by the often asymptomatic nature of hyperglycaemia, which can reduce motivation to engage with self-management behaviours.

Lifestyle factors are equally significant:

• Diet: High intake of refined carbohydrates and ultra-processed foods contributes directly to elevated postprandial glucose

• Physical inactivity: Regular exercise improves insulin sensitivity and can contribute to modest reductions in HbA1c, the extent of which depends on baseline levels, exercise type, and adherence

• Obesity: Excess adiposity, particularly visceral fat, drives insulin resistance and makes glycaemic targets harder to achieve

• Psychological wellbeing: Diabetes distress, depression, and anxiety are associated with poorer self-management and higher HbA1c levels

Psychological difficulties are more common in people with diabetes than in the general population. Both NICE NG17 (type 1) and NICE NG28 (type 2) advise that healthcare professionals routinely assess for diabetes distress, depression, and anxiety as part of ongoing diabetes care, and offer or refer for appropriate psychological support where needed. Diabetes UK provides accessible resources on emotional wellbeing for both patients and healthcare professionals. Patients experiencing significant distress should be encouraged to discuss this with their diabetes care team, who can facilitate referral to suitable support services.

How Socioeconomic and Systemic Factors Influence HbA1c

Socioeconomic deprivation, ethnicity-related health inequalities, fragmented NHS care, and reduced monitoring during the COVID-19 pandemic all contribute to higher HbA1c levels at a population level.

Socioeconomic deprivation is a well-established driver of health inequalities in diabetes management. Data from the National Diabetes Audit (NDA) consistently demonstrate that people living in more deprived areas are less likely to achieve all eight NICE-recommended care processes and are more likely to have HbA1c levels above target. Financial constraints can affect access to healthy food, physical activity facilities, and even the ability to attend regular clinic appointments — all of which have a direct bearing on glycaemic control.

Ethnicity also intersects with HbA1c outcomes in important ways. South Asian, Black African, and Black Caribbean populations in the UK have higher rates of type 2 diabetes and, in some analyses, higher average HbA1c levels compared to White British populations. These differences are multifactorial, reflecting a complex interplay of social, cultural, structural, and clinical factors, as well as differential access to culturally sensitive healthcare — rather than any single deterministic cause. NDA inequalities reports and NHS Race and Health Observatory analyses provide further detail on these patterns.

It is also important to note that HbA1c measurement may be less reliable in people with certain haemoglobin variants (such as HbS, HbC, or HbE), which are more prevalent in some ethnic communities. UK laboratory guidance advises that alternative measures — such as fructosamine or CGM-derived glucose data — should be used in these circumstances to avoid misclassification of glycaemic control.

At a systemic level, fragmentation of care between primary and secondary services, limited appointment availability, and high GP workload can all contribute to delayed treatment reviews. The shift towards remote consultations during and after the COVID-19 pandemic affected the regularity of HbA1c monitoring for some patient groups, though the impact has varied. Addressing these systemic barriers requires coordinated effort across NHS commissioning, primary care networks, and public health policy — recognising that individual clinical interventions alone are insufficient to close the gap in glycaemic outcomes.

NICE Guidance on Overcoming Barriers to HbA1c Targets

NICE recommends individualised care planning, structured diabetes education, CGM for eligible patients, psychological assessment, and timely specialist referral to address barriers to HbA1c targets.

NICE provides a structured framework for identifying and addressing barriers to glycaemic control. The key guidelines are NICE NG17 (type 1 diabetes in adults: diagnosis and management), NICE NG28 (type 2 diabetes in adults: management), and NICE NG18 (diabetes in children and young people). Central to all three is the principle of individualised care planning, which involves shared decision-making between the patient and their healthcare team to set realistic, agreed-upon targets that account for personal circumstances, comorbidities, and treatment preferences.

NICE recommends that all people with diabetes receive structured education at diagnosis and at key points in their care journey. Programmes such as DESMOND (Diabetes Education and Self Management for Ongoing and Newly Diagnosed) for type 2 diabetes and DAFNE (Dose Adjustment For Normal Eating) for type 1 diabetes are endorsed as effective tools for improving self-management skills and, in some evidence, HbA1c outcomes. However, uptake of these programmes remains suboptimal nationally, representing an ongoing systemic gap.

Regarding glucose monitoring technology, NICE NG17 recommends that real-time CGM (rtCGM) or intermittently scanned CGM (isCGM) should be offered to all adults with type 1 diabetes. For adults with type 2 diabetes, CGM or flash glucose monitoring may be appropriate for specific groups — including those on insulin with problematic hypoglycaemia, or where real-time data would support a treatment change — in line with NICE NG28 and NHS England implementation policy. Clinicians should ensure eligible patients are aware of and offered these technologies.

For patients not meeting targets despite optimised therapy, NICE advises:

• Reviewing adherence before escalating treatment

• Assessing for psychological difficulties (including diabetes distress, depression, and anxiety) and offering or referring for support where identified

• Timely referral to specialist diabetes services where targets remain unmet or complications are present

• Setting clear review timescales — typically three to six months after any treatment change — to assess response and adjust management accordingly

Urgent review or same-day referral should be arranged if any of the following are present: symptoms suggestive of diabetic ketoacidosis (DKA) or hyperosmolar hyperglycaemic state (HHS), severe or recurrent hypoglycaemia, an acute foot ulcer or infection (refer urgently to the foot protection team or multidisciplinary foot team per NICE NG19), or diabetes in pregnancy or pregnancy planning. Patients should be advised to seek urgent medical attention if they develop any of these concerns.

Practical Strategies to Support Better Glycaemic Outcomes

Simplifying treatment regimens, offering CGM to eligible patients, using proactive recall systems, and providing behavioural support are evidence-based strategies to improve HbA1c outcomes in clinical practice.

Translating guidance into practice requires a combination of clinical, educational, and behavioural strategies tailored to the individual. One of the most effective approaches is simplifying treatment regimens where possible. Reducing pill burden through combination tablets, or switching to once-daily formulations, can meaningfully improve adherence without compromising efficacy. Pharmacists play a valuable role in medicines reconciliation and adherence counselling, and their involvement in diabetes reviews is increasingly recognised within primary care network models.

Regarding self-monitoring of blood glucose (SMBG), NICE NG28 advises that routine SMBG should not be offered to all adults with type 2 diabetes. It is appropriate for those on insulin, those at risk of hypoglycaemia, during intercurrent illness, or when a short-term assessment of glycaemic response to a treatment change is needed. For adults with type 1 diabetes, CGM (rtCGM or isCGM) should be offered to all, in line with NICE NG17. For eligible adults with type 2 diabetes, CGM access is determined by NICE NG28 criteria and NHS England implementation policy; clinicians should ensure patients who meet the criteria are offered these technologies. Real-time glucose data can support behaviour change in a way that a three-monthly HbA1c result alone cannot.

From a lifestyle perspective, evidence-based interventions include:

• Low-calorie dietary programmes: The NHS Type 2 Diabetes Path to Remission Programme has demonstrated that significant weight loss can achieve HbA1c normalisation in some patients. The programme has specific eligibility criteria and requires careful medication adjustment and monitoring; patients should be referred via their GP or diabetes team and can find further information on the NHS website

• Structured physical activity: Even modest increases in daily movement can improve insulin sensitivity

• Behavioural support: Motivational interviewing techniques used by diabetes specialist nurses and health coaches can address ambivalence and support sustained change

Proactive recall systems within GP practices — flagging patients who have not attended for HbA1c monitoring or whose results are above target — are a practical systemic tool. Patients should be encouraged to contact their GP or diabetes team promptly if they notice worsening symptoms, experience frequent or severe hypoglycaemia, develop foot problems, are planning a pregnancy, or feel their current management plan is not working, as early review can prevent further deterioration in glycaemic control. Any suspected side effects from diabetes medicines should be reported to the MHRA via the Yellow Card scheme at yellowcard.mhra.gov.uk or using the Yellow Card app.

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