Does stress affect HbA1c? The short answer is yes — and understanding how is an important part of managing diabetes effectively. Stress triggers hormonal responses that raise blood glucose levels, and when stress becomes chronic, these repeated elevations can push HbA1c higher over time. HbA1c reflects average blood sugar over the preceding two to three months and is a key marker used by NHS clinicians to diagnose and monitor diabetes. Both psychological stress — such as anxiety or depression — and physical stress, such as illness or surgery, can influence glycaemic control through distinct but overlapping mechanisms.

How Stress Affects Blood Sugar Levels and HbA1c

Stress triggers hormonal responses that raise blood glucose, and if chronic, can elevate HbA1c — the two-to-three-month average blood sugar marker used by the NHS to diagnose and monitor diabetes.

Stress — whether emotional, psychological, or physical — can have a meaningful impact on blood glucose control, and by extension, on HbA1c levels. HbA1c is a blood test that reflects average blood sugar levels over the preceding two to three months. In the UK, in line with NICE guidance (NG28), an HbA1c of 48 mmol/mol (6.5%) or above on two separate occasions is used to diagnose type 2 diabetes in adults, and the test is also used routinely to monitor long-term glycaemic control in people already living with the condition.

It is important to note that HbA1c is not appropriate for diagnosing diabetes in all circumstances. NICE and WHO guidance advises against using HbA1c for diagnosis during pregnancy, in children and young people, in suspected type 1 diabetes, or in people with conditions that alter red blood cell turnover or haemoglobin structure — such as haemoglobinopathies (including sickle cell disease and thalassaemia), haemolytic anaemia, iron deficiency anaemia, or chronic kidney disease. In these situations, alternative markers such as fasting plasma glucose or an oral glucose tolerance test should be used.

When the body experiences stress, it triggers a cascade of hormonal responses that can raise blood glucose levels in the short term. If stress becomes chronic or poorly managed, these repeated glucose elevations may contribute to a higher HbA1c reading over time.

Chronic stress is associated with an increased risk of developing type 2 diabetes, though this relationship is multifactorial — mediated by both direct physiological effects and indirect behavioural changes such as poor diet, reduced activity, and disrupted sleep. Stress alone is unlikely to be the sole cause of diabetes; the relationship is complex and not fully established in terms of direct causality.

In people who already have diabetes — or who are at risk — sustained stress can make blood sugar harder to control. Diabetes UK and NICE both acknowledge that psychological wellbeing is an integral part of effective diabetes management. Understanding this relationship is the first step towards addressing it constructively.

If your HbA1c result appears inconsistent with your self-monitoring of blood glucose (SMBG) or continuous glucose monitor (CGM) readings, it is worth discussing this with your diabetes care team. Discordance between HbA1c and day-to-day readings can sometimes reflect analytical or physiological factors — such as haemoglobin variants, altered red cell turnover, or anaemia — rather than stress alone. In such cases, your clinician may consider alternative markers, such as fructosamine, in line with local policy.

The Science Behind Stress Hormones and Glucose Regulation

Cortisol and adrenaline, released during stress via the HPA axis and sympathetic nervous system, raise blood glucose through gluconeogenesis and glycogenolysis, promoting insulin resistance that can cumulatively raise HbA1c.

When the body perceives stress, the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system are activated. This triggers the release of two key stress hormones: cortisol (from the adrenal cortex) and adrenaline (epinephrine, from the adrenal medulla). Both hormones play a direct role in glucose metabolism.

• Cortisol stimulates gluconeogenesis in the liver — the production of new glucose from non-carbohydrate sources — and reduces the sensitivity of cells to insulin, a process known as insulin resistance.

• Adrenaline acutely raises circulating blood glucose primarily by stimulating hepatic glycogenolysis (the breakdown of glycogen stored in the liver) and by promoting hepatic gluconeogenesis. Muscle glycogen is broken down locally to fuel muscle activity and does not directly raise blood glucose levels in the same way.

In a healthy individual without diabetes, the pancreas compensates by releasing additional insulin to bring glucose levels back to normal. However, in people with type 1 or type 2 diabetes, this compensatory mechanism is impaired. The result is a more pronounced and prolonged rise in blood glucose.

In chronic stress states — such as work-related burnout, bereavement, or anxiety disorders — HPA axis activity can become dysregulated, contributing to sustained insulin resistance and impaired glucose regulation. The evidence on persistently elevated cortisol in chronic stress is nuanced and varies between individuals, but the cumulative effect on blood glucose can, over weeks and months, be reflected in a raised HbA1c.

NICE guidance (NG28) recommends that psychosocial factors are considered as part of holistic diabetes care. Clinicians are encouraged to explore psychological wellbeing alongside clinical markers, particularly when HbA1c results appear inconsistent with a patient's reported self-monitoring data and no analytical explanation is apparent.

Psychological and Physical Stress: Different Effects on HbA1c

Physical stress causes rapid, acute glucose spikes via counter-regulatory hormones, while psychological stress exerts a more gradual, sustained influence on HbA1c through cortisol-driven insulin resistance and indirect behavioural changes.

It is useful to distinguish between psychological stress (such as anxiety, depression, relationship difficulties, or work pressures) and physical stress (such as illness, surgery, or injury), as both can affect HbA1c, albeit through slightly different pathways.

Physical stress, such as an acute infection or surgical procedure, causes a rapid and often substantial rise in cortisol and other counter-regulatory hormones. This is why blood glucose levels frequently spike during illness — a phenomenon sometimes referred to as 'sick day' hyperglycaemia. NHS sick day rules for people with diabetes are designed specifically to help manage this risk. A single episode of physical illness is unlikely to substantially alter a three-month HbA1c, but repeated or prolonged illness can.

Important — when to seek urgent help: If you have diabetes and experience very high blood glucose readings alongside symptoms such as abdominal pain, vomiting, excessive thirst, frequent urination, drowsiness, rapid or deep breathing, or fruity-smelling breath, seek urgent medical attention immediately. These may be signs of diabetic ketoacidosis (DKA) or hyperosmolar hyperglycaemic state (HHS), both of which are medical emergencies. Call 999 or go to your nearest A&E. If you are unsure, call NHS 111. Similarly, if you experience a severe hypoglycaemic episode (very low blood sugar) that does not respond to treatment, or if someone loses consciousness, call 999 immediately.

Psychological stress tends to exert a more gradual but sustained influence. Research — including systematic reviews published in journals such as Diabetic Medicine and Diabetes Care — has found consistent associations between depression, anxiety, and elevated HbA1c in people with type 2 diabetes. The mechanisms are both direct (via cortisol-driven insulin resistance) and indirect:

• Poor sleep quality associated with stress can impair glucose regulation.

• Stress may lead to unhealthy coping behaviours such as comfort eating, reduced physical activity, increased alcohol consumption, or poor medication adherence — all of which can worsen glycaemic control.

• Diabetes distress — a specific form of emotional burden related to living with diabetes — is recognised by NICE (NG28) as a clinically significant issue. NICE recommends that psychological wellbeing is assessed and that appropriate support is offered as part of routine diabetes care.

Understanding which type of stress is most relevant to an individual helps clinicians and patients tailor their management approach accordingly.

Managing Stress to Support Better HbA1c Results

Evidence-based strategies including structured exercise, CBT, mindfulness-based stress reduction, improved sleep hygiene, and NICE-endorsed diabetes education programmes can reduce stress and support better glycaemic control.

Addressing stress as part of diabetes management is not simply about improving wellbeing — it can have a tangible effect on HbA1c outcomes. NICE guidelines for type 2 diabetes (NG28) and type 1 diabetes (NG17) both acknowledge the importance of psychological support as part of a holistic care plan.

Evidence-based strategies that may help reduce stress and support better blood glucose control include:

• Structured exercise: Physical activity reduces cortisol levels, improves insulin sensitivity, and has well-established benefits for both mental health and glycaemic control. NHS guidelines recommend that adults aim for at least 150 minutes of moderate-intensity activity (such as brisk walking) or 75 minutes of vigorous-intensity activity per week, alongside muscle-strengthening activities on two or more days per week. If you use insulin or a medication that stimulates insulin secretion (such as a sulphonylurea), speak to your diabetes team before significantly increasing your activity levels, as exercise can increase the risk of hypoglycaemia and adjustments to your medication or carbohydrate intake may be needed.

• Mindfulness-based stress reduction (MBSR): Some studies and meta-analyses suggest that mindfulness practices may modestly improve HbA1c and reduce stress in people with type 2 diabetes, though the evidence is heterogeneous and effects are generally modest. MBSR may be a useful complementary approach for some individuals.

• Cognitive behavioural therapy (CBT): NICE recommends CBT for anxiety and depression, both of which are more prevalent in people with diabetes. Treating these conditions can improve quality of life and self-management capacity, and may indirectly support better glycaemic control, though the direct effect on HbA1c is likely to be modest and mediated through improved self-care behaviours.

• Sleep hygiene: Prioritising consistent, restorative sleep supports hormonal balance and glucose regulation.

• Peer support and structured diabetes education: NICE-endorsed structured education programmes — such as DESMOND (for type 2 diabetes) and DAFNE (for type 1 diabetes) — are designed to improve self-management skills, reduce diabetes distress, and support better glycaemic outcomes. Ask your GP or diabetes team about availability in your area.

It is worth emphasising that stress management should complement — not replace — medical treatment. Medication, dietary changes, and regular monitoring remain the cornerstones of diabetes care. However, integrating psychological support into a care plan can meaningfully enhance overall outcomes.

When to Speak to Your GP About Stress and Diabetes Control

Speak to your GP or diabetes team if you notice unexplained rises in blood glucose, a higher-than-expected HbA1c, persistent low mood or anxiety, or signs of diabetes distress affecting your self-management.

If you have diabetes and are concerned that stress may be affecting your blood glucose levels or HbA1c results, it is important to raise this with your GP or diabetes care team. There is no need to wait until your next scheduled review — many GP practices and diabetes clinics welcome proactive contact between appointments.

You should consider speaking to your GP or diabetes nurse if you notice any of the following:

• Unexplained rises in blood glucose readings that do not correspond to changes in diet, activity, or medication.

• An HbA1c result that is higher than expected, particularly if your self-monitoring data suggests otherwise.

• Persistent low mood, anxiety, or feelings of being overwhelmed, especially if these are affecting your ability to manage your diabetes day to day.

• Difficulty adhering to your medication regimen due to stress, forgetfulness, or emotional fatigue.

• Signs of burnout related to diabetes management, sometimes called 'diabetes distress', which can include frustration, exhaustion, or a sense of hopelessness about your condition.

Urgent help — when to act immediately: If you experience symptoms that may indicate DKA or HHS (such as abdominal pain, vomiting, confusion, rapid breathing, or very high glucose with positive ketones), call 999 or go to A&E without delay. For severe or recurrent hypoglycaemia that does not respond to treatment, also call 999. If you are unsure whether your symptoms require emergency care, call NHS 111 for advice.

Mental health crisis: If you are experiencing thoughts of self-harm or suicide, or feel you are in immediate danger, call 999 or go to your nearest A&E. You can also call NHS 111 (option 2 for mental health), contact the Samaritans on 116 123 (free, 24 hours), or speak to your GP urgently.

Your GP can refer you to relevant support services, which may include a diabetes specialist nurse, a psychologist with experience in long-term conditions, or a structured education programme. NHS Talking Therapies (formerly IAPT) services offer CBT and other evidence-based psychological therapies for anxiety and depression, and in many areas can be accessed via self-referral without a GP referral — visit the NHS website to find your local service.

It is also worth remembering that a single elevated HbA1c does not necessarily indicate a long-term problem. Context matters, and your healthcare team is best placed to interpret your results alongside your wider circumstances. Open, honest communication about stress and mental health is an important part of effective diabetes care.

Frequently Asked Questions