Blood sugar spikes: what are they and how you can manage them

Big blood sugar spikes happen when glucose levels rapidly rise after eating sugary or high-carb foods, leading to a short energy boost followed by fatigue, brain fog and cravings.

Saga Health Insurance surveyed 500 people and partnered with Steve Bennett, a qualified health coach and Parliamentary Advisor on the House of Lords’ Food, Diet and Obesity Committee, to reveal how our eating habits affect our blood sugar levels.

The biggest sugar spikers in modern diets

Steve says: “Ultra-processed carbs like white bread, sugary cereals, pasta and baked goods lack fibre and digest rapidly into sugar. Hidden sugars in ‘healthy’ foods like granola bars, fruit juices, low-fat yoghurts and smoothies often contain as much sugar as desserts and are big spikers.

“Unexpected culprits like rice cakes (higher glycaemic index than sugar), dried fruit, sushi with white rice and even sweet potato fries can trigger large glucose spikes.”

Most get it wrong as soon as they wake up

Overnight, your body depletes its stored glucose, so by morning you're running on empty and need a sugar-balanced meal.

For breakfast, 39% of the people in our survey opt for ultra-processed carb-heavy meals like toast, cereal or pastries. These breakfast foods aren’t the best choices as Steve explains: “Blood sugar spikes are primarily caused by ultra-processed carbohydrates, especially those stripped of fibre.”

However, over a quarter (27%) of our respondents opts for something high in protein or fibre, like eggs and spinach or Greek yoghurt and berries – good options for balanced blood sugar levels in the morning according to Steve.

Enjoying a sweet treat doesn’t have to come at the cost of your health

Almost half (49%) in our survey reaches for a chocolatey snack as their preferred sweet treat. And most like it in the late afternoon as a pick-me-up between lunch and dinner.

But Steve recommends to time your treats wisely: “The best time to have a sugar-rich treat is within 30 minutes of a balanced meal. This allows your body to process the sugar more effectively and minimise spikes.”

Eating blood sugar spikers before bed is particularly disruptive

Steve says: "Our bodies become more insulin resistant in the evening, meaning the same food eaten at night causes a higher glucose response than if eaten earlier in the day.

“Nighttime spikes disrupt sleep quality, impair overnight cellular repair and contribute to morning brain fog. They also interfere with growth hormone release, which occurs primarily during deep sleep and is essential for tissue repair and metabolic health.”

Why big spikes matter

Over time, repeated big blood sugar spikes contribute to insulin resistance (where your body is less able to regulate its blood sugar levels), increasing the risk of obesity, type 2 diabetes, heart disease and even accelerated ageing.

Heart disease is the third-leading cause of death in England and Wales according to the ONS and Diabetes UK figures show that diabetes levels are at an all-time high.

How to avoid big spikes and crashes for a balanced day of eating

Steve says: “Incorporating fibre (vegetables, salads and whole grains), protein (lean meats, legumes or tofu) and healthy fats (avocado, nuts and olive oil) at every meal slows the absorption of sugars and helps maintain steady blood glucose levels.”

If you’re looking to swap a chocolate bar for a satisfying, balanced snack, Steve recommends Greek yoghurt with berries, chia seed pudding, hummus with vegetables, some nuts or a boiled egg.

Spotting blood sugar spikers

Understanding food labels during your food shop helps manage balanced blood sugar levels. Steve advises:

• More than 5g of sugar per 100g may cause moderate spikes.
• Above 10g per 100g is likely to trigger significant glucose elevation (often marked red on food labels).

Aim for products where fibre is at least half the sugar content.