How glucose and blood sugar affect your body
Glucose is your body’s main source of energy, and when you eat carbohydrates like bread, rice, fruit or milk, your body breaks them down into glucose. This glucose moves into your blood. The pancreas then releases insulin, which helps move the glucose into your muscles and liver to be used or stored. Eating too many fast-digesting carbohydrates or not being active can upset this balance, with blood sugar often rising quickly and then dropping just as fast. These ups and downs can make you feel tired and hungry, and over time, may lead to weight gain and poor heart health.
How the glycaemic index works
The glycaemic index is a 0-100 scale that shows how swiftly a carbohydrate food moves glucose into your bloodstream. Pure glucose is at the top of the scale with the value of 100.
Foods that score 55 or under sit in the low GI bracket and release their energy at a slow, steady pace. Examples include rolled oats, barley, quinoa, chickpeas, lentils, most berries, apples and leafy vegetables.
Medium-GI foods fall between 56 and 69. Whole-wheat bread, brown rice and sweet potatoes belong here and raise blood sugar a little faster yet still within a manageable range.
Anything at 70 or above counts as high GI. White bread, white rice, potatoes, fizzy drinks and sugary breakfast cereals fit this group and can spike readings within minutes.
Why avoiding big GI peaks matters
- Spike -crash cycle: High-GI foods send blood sugar soaring. Your pancreas floods the body with insulin, the sugar drops quickly, and you feel tired and hungry again soon after.
- Insulin resistance builds over time: When this spike-and-crash pattern happens most days, muscle and liver cells start to “tune out” insulin’s message. That insulin resistance is the first step towards metabolic syndrome - high fasting glucose, raised triglycerides, low HDL (“good”) cholesterol, a growing waistline and higher blood pressure.
- Fat goes to the wrong places: Surplus glucose is first tucked away under the skin. Once that storage is full, it settles around the liver, pancreas and other organs as visceral fat, fuelling inflammation and further insulin resistance.
- Low-GI choices break the chain: Swapping white bread for seeded whole-grain, or fizzy drinks for water or unsweetened tea, flattens blood-sugar peaks, reduces the insulin rush and keeps cravings in check. Large studies show people who base meals on low-GI, high-fibre carbs maintain steadier glucose and are less likely to develop Type 2 diabetes.
How everyday food choices affect your blood sugar
- Small tweaks at each meal can smooth out blood-sugar swings. Try to start with these easy swaps.
- Breakfast swap: Frosted cornflakes can spike blood sugar within 30 minutes. But if you add some protein, such as a boiled or poached egg, it will keep you fuller for longer and flatten your glucose curve.
- Lunch upgrade: Trade a white baguette sandwich for a whole-grain wrap packed with chicken and salad. You cut the meal’s GI and gain extra protein and fibre.
- Dinner tweak: Replace instant white rice with quinoa or steamed new potatoes to lower the GI while boosting minerals.
- Pair wisely: When you do fancy a higher-GI favourite such as a white baguette, eat it alongside lean protein, healthy fats (olive oil, nuts, avocado) and plenty of non-starchy veg. The mix slows digestion so blood sugar rises more gently.
Reasons why your blood sugar drifts out of balance
Eating foods like sugary cereals, white bread, biscuits or syrupy lattes can make your blood sugar rise quickly. Fizzy drinks act even faster as the sugar is absorbed almost instantly. Oversized portions, even of healthy low-GI foods, can overwhelm your system with more glucose than your muscles can clear. Add to this hours of sitting after meals, and you can be sure that muscles sit idle and sugar remains high. And if this is coupled with a lack of sleep or living under constant stress, cortisol will also be raised, prompting the liver to release extra glucose and pushing your morning levels up before breakfast.
How to spot the highs and lows of blood sugar
What signs should we be looking for that give us an indication of fluctuating blood sugar? You might notice a mid-afternoon energy crash, an hour of brain fog after lunch, intense urges for something sweet, or frequent loo trips alongside thirst. Keeping a one-week diary of meals, mood and energy shines a light on patterns. If you use a finger-prick glucose meter for other health reasons, you will see the spikes on the screen. Even without a meter, any repeated cycle of rapid hunger followed by sleepiness is a clue that blood sugar management needs attention.
Everyday tactics for steadier readings
1. Build meals around low-GI foods
Rolled or steel-cut oats, seeded whole-grain breads, beans, lentils, chickpeas, quinoa, bulgur, pearl barley, most fruits (especially berries, apples and citrus) and the whole rainbow of non-starchy vegetables stabilise glucose release.
2. Snack smarter - or better yet, skip snacks entirely
Healthy snacks like nuts, yoghurt, or hummus with vegetables are certainly a step up from sugary treats. They provide protein, fibre, and healthy fats that slow glucose release. However, avoiding snacks altogether is even better for flattening your glucose curve! Giving your body time between meals helps improve insulin sensitivity, reduces glucose variability, and encourages more stable energy levels.
3. Eat your food in the right order
The sequence in which you eat your meal can significantly affect glucose response. Starting with vegetables, followed by protein, and saving carbohydrates for last slows digestion and flattens the glucose curve.
4. Time your meals
Royal College of General Practitioners learning resources highlight evidence for time-restricted eating - closing the kitchen for 12 hours overnight (for example, 7 pm to 7 am). Start with a 10-hour fast - finish eating by 9 pm and have breakfast at 7 am - then move your evening cut-off 30 minutes earlier each week; after about four weeks you’ll reach the 12-hour window and can continue extending if you wish.
5. Move after you eat
A brisk ten-minute walk right after breakfast, lunch or dinner can lower the glucose rise by using muscles to absorb some of the circulating sugar straight away. If walking outdoors is tough, try marching on the spot, light household chores or a short online yoga flow.
6. Manage stress and sleep
Two minutes of square breathing, progressive muscle relaxation before bed or stepping outside for a daylight break lowers cortisol, helping the pancreas and liver keep glucose on an even keel.
Role of at-home testing
Even with a wholesome diet and regular movement, you may still feel roller-coaster energy or see “out-of-range” results during occasional checks. Genetics explain part of this. Variants in genes that influence insulin sensitivity, the way fat tissue stores excess glucose, or how quickly you feel full can make some people respond better to certain meal patterns than others.
MyHealthChecked's Glucose Management DNA Test analyses specific gene variants linked to insulin action, carbohydrate tolerance, appetite regulation and exercise response. Your report translates the science into practical tips: which carbohydrate range to aim for, ideal fibre goals, whether lower-GI or Mediterranean-style eating suits you best, and which workouts improve your glucose profile.
By understanding these genetic cues, you can target the strategies that work with, not against, your biology.
In summary
Balancing blood sugar is simpler than it sounds. Focus your plate on low-GI grains, beans, fruit and colourful vegetables. Combine carbohydrates with protein and healthy fat, be mindful with portions, and add gentle movement after meals. Prioritise good sleep and stress-relief practices to keep hormones aligned. If you still experience peaks and crashes - or want to tailor your plan from the outset - MyHealthChecked's Glucose Management DNA Test offers clear guidance so you can turn today’s meals into long-lasting energy.
References
1. British Dietetic Association. Glycaemic Index (GI) – Food Factsheet. London: BDA; 2020. Available from: https://www.bda.uk.com/resource/glycaemic-index.html
2. GPnotebook. Diet in Diabetes. Leeds: Oxbridge Solutions Ltd.; 2024. Available from: https://gpnotebook.com/en-IE/pages/diabetes-and-endocrinology/diet-in-diabetes
3. Royal College of General Practitioners. Intermittent Fasting as a Way of Managing Type 2 Diabetes. London: RCGP; 2020. Available from: https://elearning.rcgp.org.uk/blog/index.php?entryid=43
4. British Dietetic Association. Carbohydrates – Food Fact Sheet. London: BDA; 2021. Available from: https://www.bda.uk.com/resource/carbohydrates.html
5. British Dietetic Association. Diabetes – Type 2. London: BDA; 2021. Available from: https://www.bda.uk.com/resource/diabetes-type-2.html
6. GPnotebook. Diabetes Diet Advice for Adult Patients. Leeds: Oxbridge Solutions Ltd.; 2024. Available from: https://gpnotebook.com/pages/diabetes-and-endocrinology/diabetes-diet-advice-for-adult-patients