high sugar screening test preparation

Overview

A high sugar screening test checks your blood sugar (glucose) levels to see if they are too high. This test helps find conditions like prediabetes or diabetes early, when treatment can work best. Preparing correctly for the test—such as fasting (not eating or drinking anything except water) for a certain time—is important to get accurate results.

Yes, high sugar screening tests are very common. They are often part of routine health checks for adults, especially those with risk factors for diabetes.

Anyone can be screened for high blood sugar. It is especially recommended for adults aged 40 and over, people who are overweight, have a family history of diabetes, or have high blood pressure.

Symptoms

Common symptoms

• Feeling very thirsty a lot
• Urinating (peeing) more often than usual, especially at night
• Feeling very tired
• Blurred vision
• Unexplained weight loss

Symptoms in children

• Bedwetting or needing to go to the toilet more often
• Losing weight without trying
• Being more irritable or moody
• Having fruity-smelling breath

Symptoms in older adults

• Feeling confused or dizzy
• Having cuts or bruises that heal slowly
• Getting infections like thrush more often
• Numbness or tingling in the hands or feet

Causes

Main causes

• The body cannot make enough insulin (a hormone that helps sugar enter cells).
• The body does not use insulin properly (called insulin resistance).
• Too much sugar or carbohydrates in the diet over time.

Risk factors

• Being overweight or obese, especially around the belly
• Having a close family member (parent, sibling) with diabetes
• Being over 40 years old
• Having high blood pressure or high cholesterol
• Being from certain ethnic groups (South Asian, African-Caribbean, or Black African heritage) – these groups have a higher risk from a lower body weight

When to see a doctor

See a doctor urgently if:

• If you have any symptoms of very high blood sugar (see emergency symptoms) – seek medical help straight away.
• If you have a high sugar result and feel unwell, contact your GP or go to an urgent care centre.

Book a routine appointment if:

• If you have any of the common symptoms (such as increased thirst, frequent urination) for more than a few days, make a GP appointment.
• If you are 40 or older, you can ask your GP about a routine diabetes screening check.
• If you are pregnant or planning a pregnancy, your doctor may recommend screening.

Diagnosis

A high sugar screening test is usually a simple blood test. Your doctor will tell you which test is right for you and how to prepare.

Tests that may be done

• Fasting plasma glucose (FPG): You do not eat or drink anything (except water) for at least 8 hours before a blood sample is taken.
• Oral glucose tolerance test (OGTT): After fasting, you drink a sugary drink and have blood samples taken at intervals (often 2 hours later).
• HbA1c test: A blood sample is taken at any time; no fasting needed. It shows your average blood sugar over the past 2–3 months.

What to expect at your appointment

A small sample of blood is taken from a vein in your arm. It takes a few minutes and is usually painless. You may feel a little light-headed, but you can eat and drink normally after the test. Results may take a few days to come back. Your doctor will explain what your numbers mean.

Treatment

If your screening test shows high blood sugar, your doctor will talk to you about next steps. Treatment depends on the cause and severity, but often starts with lifestyle changes.

Self-care at home

• Follow any fasting instructions exactly as given – do not eat or drink (except water) for the required time.
• If you take any regular medicines, ask your doctor if you should take them on the morning of the test.
• Stay hydrated – you can drink plain water during the fasting period.
• Avoid alcohol and strenuous exercise for 24 hours before the test, as they can affect your blood sugar.

Medical treatments

If lifestyle changes are not enough, your doctor may prescribe medications to help control blood sugar. These are taken as pills or injections. Never change your dose or stop a medicine without talking to your healthcare team.

When is surgery considered?

Surgery is not a treatment for high blood sugar itself, but it may be needed for complications (like foot ulcers or eye problems) if blood sugar is poorly controlled over many years.

Living with this condition

If you are diagnosed with high blood sugar, you can live a full and active life. Managing it involves checking your blood sugar regularly, taking medications if prescribed, and staying aware of how food and activity affect your levels.

Lifestyle tips

• Eat balanced meals with plenty of vegetables, whole grains, and lean proteins.
• Aim for at least 150 minutes of moderate exercise each week (brisk walking, cycling, swimming).
• Get enough sleep and manage stress – both affect blood sugar.
• Keep a record of your blood sugar readings and share them with your healthcare team.

Diet and exercise

A healthy diet and regular exercise are the cornerstones of managing blood sugar. Work with a dietitian or diabetes educator to make a plan that fits your life. Even small changes, like swapping sugary drinks for water, can make a big difference.

Mental health and emotional wellbeing

Living with a long-term condition can sometimes feel overwhelming. It’s normal to feel worried or stressed about your health. If you notice changes in your mood or feel depressed, talk to your doctor. Support is available, and you are not alone.

Prevention

In many cases, you can reduce your risk of high blood sugar and diabetes by maintaining a healthy weight, eating a balanced diet, staying active, and not smoking. Even a 5–7% weight loss can cut your risk significantly.

Screening programmes

Routine screening can catch high blood sugar early, before symptoms appear. This is especially important if you have any risk factors. Talk to your GP about what screening schedule is right for you.

Complications

If left untreated

• Heart disease and stroke
• Nerve damage (peripheral neuropathy) causing numbness, pain, or weakness in your hands and feet
• Kidney damage (nephropathy) that can lead to kidney failure
• Eye damage (retinopathy) that can cause vision loss
• Foot problems such as ulcers and infections that may lead to amputation

Long-term outlook

With good management—including healthy lifestyle, regular check-ups, and medications when needed—most people with high blood sugar can prevent or delay complications and enjoy a good quality of life. Early detection through screening gives you the best chance.

Find support

International organisations

• International Diabetes Federation

Local organisations

• Diabetes UK · United Kingdom

Helplines

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