Prediabetes Symptoms: Why You Usually Feel Nothing

You've been more tired than usual, or more thirsty, and you've read that prediabetes has silent signs. Here is the honest answer first: most people with prediabetes feel nothing, and it shows up in a blood test. But if you have strong thirst, need the toilet all the time or lose weight without trying, do not wait: ask your doctor's office to check your blood sugar straight away. Anything else you notice can go in a notebook or in Sam's symptom diary as well; your symptom days then appear later in the monthly report you create as a PDF (the requirements are listed below).

This article explains why raised blood sugar stays unnoticed for so long and when not to wait. For the numbers that define prediabetes, see Prediabetes HbA1c: what your results mean. The prediabetes page lists what Sam keeps. Whether you have prediabetes is your doctor's call.

Can you feel prediabetes at all?

Usually not. The US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) says people with prediabetes usually have no symptoms. Some may have symptoms similar to those of diabetes. Diabetes UK puts it plainly: there aren't usually any prediabetes symptoms, and it is often found through a routine blood test.

The German diabetes information service diabinfo.de explains what symptoms mean when they do appear. Thirst, peeing a lot, tiredness and weakness tend to show up only when blood sugar is clearly raised. That usually means type 2 diabetes is already present.

So many people never know. About 97.6 million US adults had prediabetes in 2021, according to the NIDDK. In CDC survey data for 2017 to 2020, only 17.4 percent of adults with prediabetes had ever been told so by a health professional. Feeling fine is not an all-clear.

Why does raised blood sugar stay silent for so long?

Because the typical symptoms come late. The NHS says symptoms of high blood sugar usually come on gradually. They may only start when blood sugar gets very high. The NHS counts a fasting level over 7 mmol/L as high, which is 126 mg/dL. That is also where the diabetes range starts in US guidance.

Prediabetes sits below that. The NIDDK puts it at a fasting glucose of 100 to 125 mg/dL or an A1C of 5.7 to 6.4 percent. These ranges apply to lab tests on blood from a vein, not to home glucose meters. Other bodies draw the line a little differently. The HbA1c explainer covers why.

Even early type 2 diabetes often goes unnoticed. The NHS notes that not everyone gets symptoms, and that they may develop gradually. Germany's national guideline adds that type 2 diabetes often has few symptoms at first and that they are often misread.

Which symptoms point to much higher blood sugar?

Search for prediabetes warning signs and you will find long lists. What they mostly describe is type 2 diabetes or much higher blood sugar. The NIDDK adds that some people with prediabetes may have similar symptoms, so symptoms alone do not tell you which range you are in. The NHS, Diabetes UK and Germany's national guideline list:

• Feeling very tired.
• Peeing more than usual, particularly at night.
• Feeling thirsty all the time.
• Losing weight without trying.
• Blurred vision.
• Cuts or wounds taking longer to heal.
• Itching around the vagina or penis, or thrush that keeps coming back.
• Frequent infections, especially of the skin.

Germany's national guideline is stricter about timing than the NHS symptoms page. It names thirst, peeing more, tiredness, weight loss, new vision problems and stomach pain as symptoms that suggest diabetes. Glucose should then be measured without delay, because they can point to a medical emergency. So contact your GP or doctor's office straight away and ask for a blood sugar check. If it is closed, use your local out-of-hours doctor service (NHS 111 in the UK). Don't wait for your next routine test, and don't wait for it to pass. The other signs on this list also belong with your GP soon, even when they are not urgent.

The next section lists the signs that call for emergency help.

When is high blood sugar an emergency?

Call your local emergency number (112 in the EU, 999 in the UK, 911 in the US) if you have symptoms of high blood sugar, for example thirst or peeing more, and any of these come with them:

• Feeling or being sick.
• Stomach pain.
• Breathing more deeply or quickly than usual.
• A faster heartbeat than usual.
• Fruity-smelling breath.
• Feeling very drowsy or confused.

The NHS gives these as reasons to call 999. They can be signs of diabetic ketoacidosis, a serious condition in which harmful ketones build up in the blood. It can be life threatening. The NHS says to call even if you have never been diagnosed with diabetes. The symptoms can belong to diabetes nobody has found yet. Also call if you suddenly cannot see from one or both eyes or have sudden severe eye pain. Don't drive yourself: ask someone to drive you or call an ambulance.

Tiredness, skin and eyes: what do they mean?

Many searches are about one symptom at a time. The answer is similar for each: the sources behind this article name no sign that shows prediabetes.

Prediabetes and tiredness

Tiredness appears on type 2 diabetes lists, usually together with thirst and peeing more. On its own it says little. The NHS lists many common causes, such as too little sleep, stress, little exercise or an infection. If you have felt tired for a few weeks with no clear reason, the NHS advises seeing a GP, where a blood test can also check your blood sugar. If thirst, peeing more, weight loss or new vision problems come with it, don't wait: ask for your blood sugar to be checked straight away.

Itching and dark skin patches

The sources behind this article do not name general itching as a sign of prediabetes. For type 2 diabetes, the NHS lists itching around the vagina or penis, or thrush that keeps coming back.

Dark, velvety patches of skin in the armpits, neck or groin are called acanthosis nigricans. They can itch, and some people have small skin tags on them. The NHS says the most common cause is obesity. Others include type 2 diabetes, hormone conditions, some medicines and, rarely, cancer. The American Diabetes Association (ADA) lists acanthosis nigricans as a condition linked to insulin resistance. In adults with overweight, it is a reason to consider a blood test. Show new dark patches to your GP.

Prediabetes and your eyes

The sources name no eye sign of prediabetes. The NHS lists blurred vision as a possible sign of high blood sugar and of type 2 diabetes. For changes in vision such as blurred or double vision, the NHS advises an urgent GP appointment or NHS 111. If you suddenly cannot see from one or both eyes or have sudden severe eye pain, call your local emergency number.

Are prediabetes symptoms different in women?

The sources behind this article name no symptoms specific to women. The difference lies in risk. The NIDDK lists a history of gestational diabetes and polycystic ovary syndrome (PCOS) among the risk factors for prediabetes.

If you feel nothing, how is prediabetes found?

Only with a blood test from a vein: A1C, fasting plasma glucose or an oral glucose tolerance test. Home glucose meters are not approved for making a diagnosis, says the German Diabetes Association.

The ADA's 2026 Standards of Care set out who should be tested:

• Adults without symptoms should have their risk assessed, using risk factors or a validated risk calculator.
• Testing should be considered at any age for adults with overweight or obesity and at least one risk factor.
• Everyone else should start testing at age 35.
• If results are normal, repeat at least every 3 years, sooner if symptoms appear or risk changes.

Risk factors named by the ADA and the NIDDK include a close relative with diabetes and high blood pressure. Others are low HDL cholesterol or high triglycerides, PCOS, little physical activity and a history of gestational diabetes. The NIDDK also names age 35 or older, smoking and some medicines.

In the UK, Diabetes UK offers a type 2 diabetes risk score. If your result is high or very high, it advises seeing your GP for a blood test. The NHS Health Check invites people aged 40 to 74 without certain existing conditions every 5 years, and it may include a blood sugar test. The CDC's advice is simple: ask your doctor whether you should be tested.

What to write down before your appointment

A diary does not show whether you have prediabetes. It does give the visit something concrete: since when, on how many days, how strong. It replaces neither the blood test nor a call to your doctor's office for strong symptoms. Useful points:

• When you first noticed the symptom.
• Which days it came and how strong it was.
• How often you get up at night to pee, if that is new.
• Whether your weight has changed without trying.
• Every medicine you take.
• Whether diabetes runs in your family, and whether you had gestational diabetes.

In Sam you log such symptoms in the symptom diary. The catalog includes "Excessive thirst", "Frequent urination", "Fatigue", "Blurred vision" and "Itchy skin". You rate each per day as mild, moderate or severe. There is no time of day, no count and no free-text note. So keep a slip of paper for how often you get up at night. If a symptom is missing from the catalog, you can add it under your own name.

You create the monthly report yourself, as a PDF. It shows a calendar of your symptom days and your five most frequent symptoms. For that, allow notifications and Apple Health access, and tell the app whether you have a chronic condition. From your second report on, you also need to have recorded how you felt on at least 15 of the last 30 days. Symptom entries do not count for this. The monthly report is not a doctor report.

If you already have a lab report, add it to the Health Vault. With your consent, Sam reads HbA1c and glucose from it. When paper is enough is covered in Symptom diary: paper template or app?.

Log symptoms in Sam and bring them to your appointment

You walk into the appointment with days and strengths instead of a vague feeling, even before any test result.

• Instead of tally marks on a calendar: you log thirst, frequent urination, fatigue or blurred vision in the symptom diary for each day they happen, as mild, moderate or severe.
• Instead of recalling weeks from memory: the monthly report you create as a PDF (the requirements are listed above) shows your symptom days on a calendar and your five most frequent symptoms.
• Instead of lab sheets in a drawer: you add lab reports to the Health Vault, and with your consent Sam reads HbA1c and glucose from them.

Sam does not measure blood sugar and can't tell you whether you have prediabetes. A diary entry does not replace calling your doctor's office. More on the prediabetes page.

Try Sam for free

Sam is a wellness companion, not a medical device. It does not diagnose, treat, cure or prevent any disease or health condition. Always consult a qualified professional for medical decisions.

Related reading

• Prediabetes HbA1c: what your results mean
• Prediabetes: what to do next after your result
• Symptom diary: paper template or app?
• Can Apple Watch measure blood sugar?
• Doctor appointment checklist for a chronic condition

Sources

Updated: October 2026

• NIDDK: Insulin Resistance & Prediabetes (last reviewed March 2025)
• Diabetes UK: Prediabetes symptoms (reviewed 27 January 2026)
• diabinfo.de (Helmholtz Munich, German Diabetes Center, German Center for Diabetes Research): What is prediabetes? (as of 24 May 2023)
• CDC: Diabetes Report Card: Prediabetes (last reviewed 17 May 2022, archived page) and Prediabetes: Your Chance to Prevent Type 2 Diabetes (26 December 2024)
• American Diabetes Association: 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes 2026, Diabetes Care 2026; 49 (Suppl 1) (recommendations 2.11 to 2.12c, table 2.5)
• NHS: Type 2 diabetes: symptoms (reviewed 10 February 2025), High blood sugar (hyperglycaemia) (reviewed 17 March 2026) and Diabetic ketoacidosis (reviewed 8 June 2023)
• NHS: Tiredness and fatigue (reviewed 2 June 2023), Acanthosis nigricans (reviewed 4 July 2024), Vision loss (reviewed 28 August 2025) and NHS Health Check (reviewed 14 August 2023)
• German Medical Association, KBV, AWMF: National Disease Management Guideline Type 2 Diabetes, version 3.0 (2023), chapter 4 (table 9, recommendation 4-5 on people with symptoms; in German)
• German Diabetes Association (DDG): Landgraf R et al., Definition, classification, diagnosis and differential diagnosis of diabetes mellitus: Update 2025 (PDF), Diabetologie und Stoffwechsel 2025; 20: S127-S143 (measuring systems for diagnosis; in German)