Fasting Blood Glucose Level 120: What It Means

A fasting blood glucose level of 120 mg/dL (approximately 6.7 mmol/L) sits above the normal range and places you in the territory clinicians call non-diabetic hyperglycaemia, sometimes referred to as prediabetes or impaired fasting glucose. While a single reading at this level does not confirm a diagnosis, it is clinically significant and should not be ignored. This article explains what the result means in UK clinical terms, what symptoms to watch for, how diet and lifestyle can help, when to see your GP, and what tests or treatments the NHS may offer next.

What does a fasting blood glucose level of 120 mg/dL actually mean?

A fasting blood glucose of 120 mg/dL (6.7 mmol/L) falls within the UK non-diabetic hyperglycaemia range of 6.1 to 6.9 mmol/L, indicating impaired fasting glucose that requires further investigation but does not alone confirm diabetes.

A fasting blood glucose level of 120 mg/dL (approximately 6.7 mmol/L in UK units) falls above the normal range and sits within the territory that clinicians associate with non-diabetic hyperglycaemia (NDH), sometimes also referred to as impaired fasting glucose or prediabetes. In the UK, blood glucose is routinely measured in millimoles per litre (mmol/L) rather than milligrams per decilitre (mg/dL), so it is worth knowing that 120 mg/dL converts to roughly 6.7 mmol/L.

UK diagnostic thresholds, as set out by the NHS and aligned with WHO criteria, are broadly as follows: a normal fasting plasma glucose is below 6.0 mmol/L; non-diabetic hyperglycaemia (NDH) or impaired fasting glucose is in the range of 6.1 to 6.9 mmol/L (WHO IFG definition); and a fasting plasma glucose of 7.0 mmol/L or above, confirmed on a separate day in someone without symptoms, is consistent with a diagnosis of type 2 diabetes. For NHS Diabetes Prevention Programme (NHS DPP) referral purposes, the fasting glucose criterion used is often 5.5 to 6.9 mmol/L, which is broader than the WHO IFG range. A reading of 6.7 mmol/L falls within both ranges.

A single reading at this level does not automatically confirm a diagnosis. Results can be affected by factors such as recent illness, stress, certain medications, or an insufficiently long fast (less than eight hours). However, a reading at this level is clinically significant and warrants further investigation rather than being dismissed.

Non-diabetic hyperglycaemia indicates that the body is struggling to regulate blood sugar efficiently, often because cells have become less responsive to insulin, a process known as insulin resistance. Without intervention, NDH carries a meaningful risk of progressing to type 2 diabetes, though this progression is not inevitable and lifestyle changes can be highly effective at this stage.

What symptoms should I look out for at this blood sugar level?

Most people with a fasting glucose of 6.7 mmol/L have no symptoms; when present, signs can include increased thirst, frequent urination, fatigue and blurred vision, though these are non-specific and require GP assessment.

Many people with a fasting blood glucose of around 6.7 mmol/L experience no symptoms at all, which is one reason why non-diabetic hyperglycaemia often goes undetected without routine testing. The absence of symptoms does not mean the reading is harmless, and it is precisely this silent nature that makes regular monitoring important. Diagnosis relies on blood tests, not on symptoms.

That said, some individuals do notice early signs that may be associated with elevated blood glucose. These can include:

• Increased thirst and a dry mouth, even after drinking adequate fluids

• Passing urine more frequently, particularly at night

• Fatigue or low energy, especially after meals

• Blurred vision, which can occur when fluctuating glucose levels temporarily affect the lens of the eye

• Difficulty concentrating or a feeling of mental fogginess

• Slow healing of minor cuts or grazes

These symptoms are non-specific and can have many other causes, so they should not be used to self-diagnose. Several of them are more commonly associated with sustained hyperglycaemia at diabetic levels rather than with NDH. However, if you are experiencing several of these alongside a known elevated fasting glucose reading, it is worth discussing them with your GP.

Symptoms tend to become more pronounced as blood glucose rises further. At the NDH stage, the body is still compensating to some degree, which is why many people feel entirely well. This makes routine blood tests, particularly for those with risk factors such as a family history of diabetes, obesity, or a sedentary lifestyle, an important part of preventive healthcare.

How can I bring my fasting glucose down through diet and lifestyle?

Reducing refined carbohydrates, increasing physical activity to at least 150 minutes per week, and achieving modest weight loss of 5 to 10 per cent can significantly lower fasting glucose and reduce progression risk at the NDH stage.

Fasting blood glucose at the level of 6.7 mmol/L can often be meaningfully reduced through sustained changes to diet and physical activity, and evidence consistently shows that lifestyle intervention at the non-diabetic hyperglycaemia (NDH) stage can delay or prevent progression to type 2 diabetes.^[16][17] NICE guidance NG215 (Type 2 diabetes: prevention in people at high risk) recommends that people identified as being at high risk are offered a referral to an intensive lifestyle change programme, such as the NHS Diabetes Prevention Programme.

Dietary adjustments that may help include:

• Reducing intake of refined carbohydrates and added sugars, such as white bread, sugary drinks, pastries and processed cereals

• Choosing higher-fibre carbohydrates, such as wholegrains, legumes, vegetables and fruit, which cause a slower rise in blood glucose, in line with the NHS Eatwell Guide

• Eating regular, balanced meals rather than skipping meals, which can cause glucose fluctuations

• Reducing portion sizes, particularly of starchy foods

• Limiting alcohol, which can impair glucose regulation

Physical activity is equally important. Muscle tissue uses glucose for energy, and regular exercise improves insulin sensitivity. The UK Chief Medical Officers' Physical Activity Guidelines recommend at least 150 minutes of moderate-intensity activity per week, such as brisk walking, cycling or swimming.^[5][6] Resistance exercise, such as bodyweight exercises or light weights, can also be particularly effective at improving glucose metabolism.

Weight management plays a significant role. Evidence cited in NICE NG215 and NHS DPP materials indicates that even a modest reduction in body weight of 5 to 10 per cent can produce clinically meaningful improvements in fasting glucose for those who are overweight.^[8][16] Smoking cessation and stress management are also relevant, as both chronic stress and smoking can adversely affect blood glucose regulation.

Your GP can refer you to the NHS Diabetes Prevention Programme (NHS DPP), a structured, evidence-based programme offering dietary advice, physical activity support and behaviour change strategies, which is available to people in England who meet the eligibility criteria.

When should I see a GP about a fasting blood glucose reading of 120?

See your GP promptly if you have a fasting glucose of 6.7 mmol/L, even without symptoms, as clinical review and repeat testing are needed; seek urgent care if vomiting, confusion or rapid breathing develop.

You should see your GP if you have received a fasting blood glucose reading of 120 mg/dL (6.7 mmol/L), even if you feel well, because this level warrants clinical review and likely repeat testing. A single elevated result is not sufficient for a diagnosis, but it is sufficient reason to seek professional assessment. Do not wait for symptoms to develop before making an appointment.

You should contact your GP promptly if you notice any of the following alongside an elevated reading:

• Symptoms of high blood glucose such as persistent thirst, frequent urination, unexplained weight loss or extreme fatigue

• A reading that has risen further on home monitoring

• A personal or family history of type 2 diabetes, polycystic ovary syndrome, or cardiovascular disease

• You are pregnant or planning a pregnancy, as blood glucose targets are stricter during pregnancy; if you are pregnant, contact your midwife or antenatal team rather than waiting for a routine GP appointment

If you develop symptoms of very high blood glucose, such as vomiting, confusion, rapid breathing or severe abdominal pain, seek urgent medical attention by calling 999 or going to A&E. These symptoms are not expected at the NDH level and may indicate a serious complication such as diabetic ketoacidosis or hyperosmolar hyperglycaemic state, both of which require immediate care. For non-emergency concerns outside of GP hours, NHS 111 can provide advice.

For those considering a structured approach to managing their glucose through an online service, Bolt Pharmacy is a GPhC-registered online pharmacy (GPhC registration covers Great Britain; pharmacy services in Northern Ireland are regulated by the PSNI) offering online weight-management consultations, with prescriber review and pharmacist support, which may be relevant for those whose elevated glucose is linked to excess weight. Any weight-management medicine would only be prescribed where clinically appropriate following a consultation. However, a GP review remains the essential first step for any new or unexplained blood glucose result.

What tests and treatments might the NHS offer next?

The NHS will typically arrange an HbA1c test and possibly a repeat fasting glucose; if NDH is confirmed, referral to the NHS Diabetes Prevention Programme is recommended under NICE NG215, while confirmed type 2 diabetes is usually managed with lifestyle changes and metformin.

Following a fasting blood glucose of 6.7 mmol/L, the NHS is likely to offer further investigation to clarify your glucose status and assess your overall metabolic health. The most commonly used confirmatory test is the HbA1c (glycated haemoglobin) test, which reflects average blood glucose over the preceding two to three months.^[9] According to NHS and NICE NG28 criteria, an HbA1c of 42 to 47 mmol/mol indicates non-diabetic hyperglycaemia (NDH), while an HbA1c of 48 mmol/mol or above, confirmed on a separate occasion in someone without symptoms, is consistent with a diagnosis of type 2 diabetes.

It is important to note that HbA1c is not reliable in certain circumstances, including pregnancy, haemoglobinopathies (such as sickle cell disease or thalassaemia), haemolytic anaemia, recent significant blood loss or transfusion, and advanced chronic kidney disease. In these situations, a fasting plasma glucose test or an oral glucose tolerance test (OGTT) may be used instead. Your GP will advise on the most appropriate test for your circumstances.

Your GP may also arrange:

• A repeat fasting plasma glucose test on a separate day to confirm the result

• A full lipid profile and blood pressure check, as cardiovascular risk is often elevated alongside impaired glucose regulation

• Kidney function tests (urea and electrolytes) and a urine albumin-to-creatinine ratio to check for early kidney involvement

• A body mass index (BMI) assessment and waist circumference measurement

If non-diabetic hyperglycaemia is confirmed, NICE NG215 recommends referral to the NHS Diabetes Prevention Programme (NHS DPP), a structured, evidence-based programme offering dietary advice, physical activity support and behaviour change strategies, which has been shown to significantly reduce the risk of progression to type 2 diabetes.

If a diagnosis of type 2 diabetes is confirmed, treatment will typically begin with lifestyle intervention and, in most cases, the addition of metformin, a well-established oral medication that reduces glucose production in the liver and improves insulin sensitivity.^[19][11] Initiation and dosing of metformin is guided by NICE NG28 and will be individualised to your circumstances, including any relevant comorbidities and kidney function.^[11][12] At diagnosis, you will also be referred for NHS diabetic eye screening. Your GP or a diabetes specialist nurse will guide you through the management plan, which will include regular monitoring of HbA1c, blood pressure, cholesterol, kidney function and eye health.

Scientific References

1. Type 2 diabetes worldwide according to the new classification and criteria.
2. Type 2 diabetes: prevention in people at high risk (PH38) – Recommendations.
3. Type 2 diabetes: prevention in people at high risk (PH38) – Guideline overview.
4. Health matters: preventing Type 2 Diabetes.
5. Physical activity guidelines: UK Chief Medical Officers' report (full report).
6. UK Chief Medical Officers' physical activity guidelines (guidance text).
7. Physical activity guidelines for adults aged 19 to 64.
8. Overweight and obesity in adults.
9. HbA1c | Information for the public | Type 1 diabetes in adults (NG17).
10. Population level impact of the NHS Diabetes Prevention Programme.
11. Type 2 diabetes in adults: management (NG28).
12. Type 2 diabetes in adults: management (NG28) – Visual summary: choosing medicines for first-line and further treatment.
13. Diabetic eye screening.
14. Diabetic eye screening: programme overview.
15. Navigating the discordance: a comprehensive review of HbA1c-glycemia mismatch in clinical practice. Diabetes Research and Clinical Practice.
16. Reduction in the Incidence of Type 2 Diabetes with Lifestyle Intervention or Metformin.
17. Lifestyle Intervention With or Without Lay Volunteers to Prevent Type 2 Diabetes.
18. Preventing the progression of pre-diabetes to type 2 diabetes (PH38) – Evidence review R1: identification and risk assessment of adults with prediabetes.
19. Metformin in skin diseases: the role of gut microbiota and immune response. Pharmacological Reports.

Frequently Asked Questions