What Is a Good Glucose Number? UK Ranges

What is a good glucose number? For most healthy adults in the UK, a fasting blood glucose of 4.0 to 5.9 mmol/L is considered normal, with levels rising after meals before returning to this range. Understanding what your readings mean, how targets differ if you have diabetes, and what influences blood sugar day to day can help you make sense of results from a home monitor or health check. This article explains UK glucose thresholds, personalised targets for people with diabetes, and practical steps to support healthy blood sugar levels.

What is a good glucose number for most adults in the UK?

A fasting blood glucose of 4.0 to 5.9 mmol/L is normal for most healthy UK adults; a level of 7.0 mmol/L or above on two occasions indicates diabetes. Results should be confirmed by laboratory venous plasma testing.

For most healthy adults in the UK, a fasting blood glucose level of between 4.0 and 5.9 mmol/L is generally considered within the normal range, and a result below 7.8 mmol/L at two hours during a standard 75 g oral glucose tolerance test (OGTT) is used as a diagnostic threshold for normal glucose tolerance. These figures are referenced by Diabetes UK and align with NHS diagnostic guidance, though individual laboratory reference intervals may vary slightly. Blood glucose is measured in millimoles per litre (mmol/L) in the UK, which differs from the mg/dL unit used in the United States, so it is important to use the correct scale when interpreting results.

Blood glucose naturally fluctuates throughout the day. It tends to be at its lowest first thing in the morning before eating (known as a fasting level) and rises after meals as carbohydrates are digested and absorbed. In people without diabetes, the body regulates these fluctuations tightly through the hormones insulin and glucagon, keeping levels within a narrow range.

The threshold for impaired fasting glucose (IFG) under WHO criteria is 6.1 to 6.9 mmol/L. The UK also uses the broader concept of non-diabetic hyperglycaemia (NDH), which may be identified by a fasting glucose of 5.5 to 6.9 mmol/L or an HbA1c of 42 to 47 mmol/mol. Either finding warrants further assessment by a GP. A fasting level of 7.0 mmol/L or above on two separate occasions, or a random glucose of 11.1 mmol/L or above alongside symptoms, is consistent with a diagnosis of diabetes; an HbA1c of 48 mmol/mol or above on two occasions is also diagnostic. These thresholds are set out in NHS and WHO guidance.

If you receive an unexpected result from a home monitor or a health check, speak to your GP rather than drawing conclusions from a single reading alone. Home capillary readings are not equivalent to laboratory venous plasma measurements and should be confirmed with a formal laboratory test before any diagnosis is made.

How do blood sugar targets differ if you have diabetes?

People with diabetes have personalised targets; NICE recommends a fasting glucose of 5.0 to 7.0 mmol/L for type 1 and an HbA1c of 48 mmol/mol for type 2 managed without hypoglycaemia risk. Targets are adjusted individually based on treatment and risk.

People living with diabetes have personalised glucose targets that differ from the general population ranges, because both persistently high and frequently low blood sugar carry specific risks. NICE guidance (NG17) recommends that adults with type 1 diabetes aim for a fasting glucose of 5.0 to 7.0 mmol/L and a level of 5.0 to 9.0 mmol/L at least 90 minutes after eating. For adults with type 2 diabetes managed with diet alone or with medications that do not cause hypoglycaemia, NICE (NG28) recommends a target HbA1c of 48 mmol/mol (6.5%), with self-monitored glucose targets agreed individually with a clinician. Where insulin or sulfonylureas are used, a less stringent HbA1c target of 53 mmol/mol (7.0%) is often appropriate to reduce the risk of hypoglycaemia, though targets should always be individualised.

For people using insulin or sulfonylureas, which carry a risk of hypoglycaemia, targets are often set slightly higher to reduce the chance of blood sugar falling dangerously low. Targets may also be adjusted for older adults, those with frequent hypoglycaemia, people with significant comorbidities, or those who are pregnant, as the risks and benefits of tight control differ across these groups.

HbA1c is a blood test that reflects average glucose control over the preceding two to three months and is the primary monitoring tool used in NHS diabetes care. It is expressed in mmol/mol in the UK. Self-monitoring of blood glucose using a finger-prick device or a continuous glucose monitor (CGM) provides real-time information and is particularly valuable for people on insulin. Your diabetes care team will help you interpret your readings in the context of your treatment plan and lifestyle, so always discuss targets with them rather than applying general population figures to your own management.

If you suspect that a medicine you are taking is causing side effects such as hypoglycaemia, you can report this to the MHRA via the Yellow Card scheme at yellowcard.mhra.gov.uk.

What do your glucose readings actually mean?

A fasting reading below 4.0 mmol/L warrants attention, 4.0 to 5.9 mmol/L is normal, 6.0 to 6.9 mmol/L suggests impaired fasting glucose, and 7.0 mmol/L or above is consistent with diabetes if confirmed. Context, timing and patterns matter more than single readings.

A single glucose reading provides a snapshot of your blood sugar at one moment in time, and its meaning depends heavily on when it was taken, what you had eaten beforehand, and your individual health context. A fasting reading taken first thing in the morning before any food or drink (other than water) is the most standardised and comparable measurement for most people. A post-meal reading, typically taken one to two hours after the start of a meal, reflects how your body handles carbohydrate intake, though home post-meal targets for people with diabetes should be agreed individually with a clinician rather than compared directly to OGTT-based diagnostic thresholds.

The table below summarises how NHS and WHO guidance broadly categorises fasting glucose results for adults without a prior diabetes diagnosis. These categories are based on laboratory venous plasma measurements; home capillary readings may differ and should be interpreted with care:

• Below 4.0 mmol/L: A low reading that warrants attention. If you have symptoms such as shakiness, sweating or confusion, treat promptly and seek advice. A reading below 3.0 mmol/L or any severe symptoms require urgent action. If you have no symptoms, confirm the result and discuss with your GP.

• 4.0 to 5.9 mmol/L: Within the normal fasting range for most healthy adults.

• 6.0 to 6.9 mmol/L: May indicate impaired fasting glucose or non-diabetic hyperglycaemia; warrants GP review and further laboratory testing. Note that WHO IFG criteria begin at 6.1 mmol/L, while UK NDH programmes may use a lower threshold of 5.5 mmol/L.

• 7.0 mmol/L or above: Consistent with diabetes if confirmed on a second laboratory test or alongside symptoms.

For people already diagnosed with diabetes, readings outside their agreed target range are not automatically cause for alarm but should be noted and discussed with their care team. Patterns over time are more informative than individual readings. A continuous glucose monitor or a structured diary of finger-prick results can help identify trends linked to meals, activity, stress or medication timing. If you are unsure how to interpret your readings, your GP or diabetes nurse can provide guidance tailored to your situation.

What can cause your blood sugar to go too high or too low?

Hyperglycaemia is commonly caused by excess carbohydrate intake, inactivity, illness, stress or missed diabetes medication; hypoglycaemia most often occurs in people taking insulin or sulfonylureas. Severe symptoms or persistent unexplained readings require prompt medical advice.

Blood sugar rises above the normal range (hyperglycaemia) when the body cannot produce enough insulin, cannot use insulin effectively, or when glucose intake exceeds the body's capacity to manage it. Common triggers include eating large amounts of refined carbohydrates or sugary foods, physical inactivity, illness or infection, significant psychological stress, and certain medicines such as corticosteroids. In people with diabetes, missed doses of insulin or oral medication are a frequent cause.

Blood sugar falls below the normal range (hypoglycaemia) most commonly in people taking insulin or sulfonylurea medicines. Symptoms of hypoglycaemia include shakiness, sweating, confusion, palpitations and, in severe cases, loss of consciousness.^[2] Causes include taking too much insulin, skipping or delaying meals, drinking alcohol without eating, and unplanned vigorous exercise. People without diabetes can also experience low blood sugar, though this is less common; recurrent unexplained episodes should be discussed with a GP.

Several other factors can influence glucose levels in ways that are not always obvious:

• Sleep quality: Poor or insufficient sleep can impair insulin sensitivity.^[11]

• Hormonal changes: The menstrual cycle, menopause and thyroid disorders can all affect glucose regulation.

• Illness, stress and dehydration: These can raise blood glucose directly. Home glucose meters may also give inaccurate readings in certain conditions, including extremes of haematocrit; refer to your meter's instructions for use or seek advice from your pharmacist or GP if you are unsure whether a reading is reliable.^[10]

• Timing of testing: Results vary significantly depending on whether a test is fasting or post-meal.

If you experience symptoms of severe hypoglycaemia or persistent hyperglycaemia that you cannot account for, contact your GP or NHS 111. People at risk of type 1 diabetes who have persistently high readings alongside symptoms such as excessive thirst, frequent urination or feeling unwell should seek prompt medical assessment, as ketone testing may be needed. In an emergency, such as loss of consciousness or seizure, call 999 immediately.

How can you keep your glucose levels within a healthy range?

A balanced diet limiting refined sugars, at least 150 minutes of moderate aerobic activity per week, and stress management all help maintain healthy glucose levels. People with non-diabetic hyperglycaemia may be referred to the NHS Diabetes Prevention Programme.

Maintaining blood glucose within a healthy range involves a combination of dietary choices, physical activity, stress management and, where relevant, medication adherence. Eating a balanced diet that limits refined sugars and ultra-processed foods, includes plenty of vegetables, wholegrains, lean protein and healthy fats, and spaces meals evenly throughout the day helps to prevent large post-meal glucose spikes. The NHS Eatwell Guide provides a practical framework for balanced eating that supports stable blood sugar.

Regular physical activity improves insulin sensitivity, meaning the body uses glucose more efficiently. The UK Chief Medical Officers recommend that adults aim for at least 150 minutes of moderate-intensity aerobic activity per week, alongside muscle-strengthening activities on two or more days.^[7][8] Even a short walk after meals has been shown to reduce post-meal glucose rises.^[12][13] Managing psychological stress is also relevant, as stress hormones such as cortisol raise blood glucose directly.

For people with type 2 diabetes or at high risk of developing it, structured weight management can significantly improve glucose control. NICE prevention guidance supports referral to the NHS Diabetes Prevention Programme (NHS DPP) for those identified with non-diabetic hyperglycaemia.^[6] Pharmacological treatment is not routinely recommended for prediabetes but may be considered for people with diagnosed type 2 diabetes where lifestyle measures alone are insufficient, following clinical assessment. A prescriber may consider a range of options in that context, including medicines that support both glucose control and weight management. Bolt Pharmacy is a GPhC-registered UK online pharmacy offering online weight-management consultations, with prescriber review and pharmacist support, where clinically appropriate options may be discussed.

If you are monitoring your glucose at home and consistently seeing readings outside your target range despite lifestyle efforts, speak to your GP or diabetes care team. Do not adjust prescribed medication doses without clinical advice, and contact NHS 111 if you are unsure whether a reading requires urgent attention.

Scientific References

1. High blood sugar (hyperglycaemia).
2. Low blood sugar (hypoglycaemia).
3. Type 1 diabetes in adults: diagnosis and management (NG17) – Recommendations.
4. Blood glucose management – Type 2 diabetes in adults (NG28).
5. Type 2 diabetes in adults: management – Recommendations (NG28).
6. Type 2 diabetes in adults – Quality standards (QS209): Preventing type 2 diabetes.
7. Physical activity guidelines: UK Chief Medical Officers' report.
8. UK Chief Medical Officers' physical activity guidelines (full guidance).
9. Physical activity guidelines for adults aged 19 to 64.
10. Device-specific vigilance guidance: in vitro diagnostic (IVD) blood glucose monitors.
11. Impact of Sleep on Glucose Metabolism in Individuals With Overweight or Obesity: A Systematic Review.
12. Assessing the Impact of Arm Rotation with Walking Exercise on Blood Glucose and HbA1c Levels in Patients with Diabetes Mellitus: A Hospital Based Study.
13. Interrupted sitting at work can alter postprandial glucose, triglycerides and non-esterified fatty acids (NEFA).

Frequently Asked Questions