People whose blood sugar was normal by the standard tests wore glucose monitors for a few weeks. Their levels climbed into the prediabetic range 15% of the time, and into the diabetic range 2% of the time. The standard tests had missed all of it.
Your blood sugar is a moving picture, and a yearly snapshot shows one frame. In 800 people who logged nearly 47,000 meals, the same meal sent one person's glucose soaring and barely moved another's. Ahead: the signs that mean it's time for a test, how low-carb, keto and carnivore eating stop blood sugar spikes, the order of eating that halves a spike, the ten-minute habit after dinner, how much weight loss it takes to put type 2 into remission, and what one short night does to your insulin.
What a spike does
Eat something starchy or sweet and the sugar floods into your blood. "Glucose" comes from the Greek gleûkos, sweet wine. Your pancreas answers with insulin to push it into your cells. "Insulin" comes from the Latin insula, island, after the tiny islands of cells in the pancreas that make it, first described in 1869.
In January 1922, in Toronto, 13-year-old Leonard Thompson became the first person treated with insulin. He lived another thirteen years.
A big, fast rise brings a big insulin response, and often a dip afterwards that leaves you tired, foggy and hungry again. Over the years, a diet that keeps insulin working overtime goes hand in hand with insulin resistance, where your cells respond less and less. That's the road to type 2 diabetes.
Check where you stand
The road is easy to miss. In the United States, 115.2 million adults have prediabetes, and in a 2017–2020 count, fewer than one in five people with it had been told. A fasting test shows one moment. HbA1c, the three-month average, adds the longer view.
Testing for sugar is an old idea. In ancient India, the condition was named madhumeha, "honey urine", for the sweet taste of the urine, and the "mellitus" in diabetes mellitus is Latin for honey-sweet. These days a blood test does the tasting.
Some signs mean you should get your blood sugar checked soon: feeling tired all the time, peeing more than usual, constant thirst, losing weight without trying, blurred vision, cuts that heal slowly, and itching or thrush that keeps coming back. They can creep up slowly, and some people have none at all.
Smoking raises the odds too. Across 88 studies with nearly six million people, smokers were 37% more likely to develop type 2 diabetes than people who had never smoked. For former smokers, the extra risk fell to 14%.
Next time you have blood taken, ask for an HbA1c alongside the fasting glucose. An lets you check it yourself in between.
The fix starts on your plate.
1. Cut the carbs: low-carb, keto or carnivore
Eating fewer of the foods that cause spikes is the most direct way to flatten them, and you can go as far as suits you.
The idea is older than you'd think. In 1863, William Banting, a London undertaker, published a pamphlet on how he lost weight by cutting starch and sugar. It sold so well that "Do you bant?" came to mean "Are you dieting?", and in Swedish banta still means to diet.
Low-carb means cutting back hard on sugar, bread, pasta, rice, potatoes and breakfast cereal, and building meals on meat, fish, eggs and vegetables. When 23 tests in people with type 2 diabetes were pooled, those on low-carb diets were far more likely to bring their long-term blood sugar back below the diabetes line after six months: 57% against 31% on other diets, counting people still on medication. By a year the data were thin and the gap had shrunk. Jason Fung's makes the case for fewer carbs and longer gaps between meals.
Keto takes carbs so low that your body runs mainly on fat and makes ketones to fuel the brain. In the same pooled tests, the strictest low-carb diets brought real weight loss to the people who stuck with them, and little to those who drifted. The diet works when you keep to it.
Carnivore is the far end: meat, fish and eggs, and little else. In a survey of 2,029 adults who had eaten this way for at least six months, most of them for over a year, those with diabetes reported lower blood sugar and needed less medication. That's self-reported and from enthusiasts, so treat it as a signal worth testing on yourself. Paul Saladino's lays out the case.
If you take medication that lowers blood sugar, cutting carbs can push it too low. Some diabetes tablets, the ones whose names end in "-gliflozin", can also cause a dangerous build-up of ketones on keto, even when blood sugar looks normal. Make the change together with whoever manages your medication.
For one week, swap your usual breakfast for eggs, and notice how long you stay full.
2. Watch the drinks and the hidden sugar
Whichever level you choose, start with the obvious offenders: sugar, sweet drinks, milk and anything sold as a "snack".
Count fruit juice among the sweet drinks. In three large groups of American health workers followed for decades, more fruit juice went with a higher risk of type 2 diabetes, while whole fruits such as blueberries, grapes and apples went with a lower one.
Milk belongs on that list too. Its natural sugar, lactose, makes up nearly 5% of every glass, about three teaspoons in a large one. Milk also stirs up insulin out of all proportion to its sugar: in healthy volunteers, milk products barely raised blood sugar, yet they pushed insulin about as high as white bread did.
The healthy-looking drinks are often the worst. On the glycaemic index, where pure glucose scores 100, rice milk scored between 79 and 92, and one oat milk scored 69. Yogurt and kefir drinks carry the same lactose as milk and the same outsized insulin response, and flavoured ones add sugar on top. A fruit smoothie scored around 68, and coconut water 55. They're sugary drinks with a healthy label.
Sugar hides in savoury and "healthy" foods too. Ketchup is about a fifth sugar, and plain granola bars are over a quarter. Read the label on sauces, granola, cereal bars and anything sold as "low-fat".
Sugar-free sweeteners are no free pass either. When 120 healthy adults took small daily amounts of saccharin, sucralose, aspartame or stevia for two weeks, saccharin and sucralose made their blood sugar response to glucose worse, and how much depended on each person's gut bacteria.
Coffee can make a meal's spike worse. In 14 daily coffee drinkers with type 2 diabetes, caffeine taken before a meal made their blood sugar rise 21% higher afterwards, and their insulin 48% higher. Without a meal, it changed little.
Alcohol needs care as well. Beer and sweet mixers bring their own carbs, and if you take insulin or tablets that lower blood sugar, alcohol stops your liver from releasing stored sugar, raising the risk of a low for up to a day after drinking.
For one week, drink water, and read the label on every sauce and snack bar you buy.
3. Eat the protein first
Order matters. People with type 2 diabetes ate the same meal on three days. When they ate the meat and vegetables first and the bread and potatoes ten minutes later, their glucose spike was about half the size of the day they ate the carbs first.
Protein before the meal works too. People with type 2 diabetes who drank a whey protein shake before a high-carb breakfast had glucose 28% lower over the next three hours than on a day they drank water.
At your next meal, finish the meat and vegetables before you touch the bread or potatoes.
4. Walk after you eat
Your muscles are the biggest sugar sponge you own, and moving them soaks glucose out of your blood. Adults with type 2 diabetes who walked for ten minutes after each meal had lower blood sugar after eating than when they walked the same total in one go each day. After dinner, the biggest and laziest meal, the difference was largest.
After dinner tonight, walk for ten minutes before you sit down.
5. Build the muscle that soaks it up
Bigger, busier muscles give that sugar somewhere to go. Across 47 tests with 8,538 people with type 2 diabetes, structured exercise lowered HbA1c, the test that averages your blood sugar over about three months, by about 0.7 points. Cardio, weight training and a mix of both all worked.
Start with two short strength sessions a week: squats, push-ups and carrying something heavy.
6. Lose the weight that's driving it
If you carry extra weight, losing it can do more than any single habit. In a UK trial with 306 people who had type 2 diabetes, an intensive weight-loss programme put 46% of them into remission after a year, off all diabetes medication, against 4% on usual care. The more they lost, the better their odds: remission came for 86% of those who lost 15 kg or more, 57% of those who lost 10 to 15 kg and 34% of those who lost 5 to 10 kg. None of those who gained weight got there.
The trial used a short spell of low-calorie shakes. The low-carb, keto and carnivore approaches above are other routes to the same weight loss.
Weigh yourself once a week, on the same morning, and watch the trend.
7. Guard your sleep and your eating window
One short night is enough to show. Healthy people who got four hours' sleep were measurably more insulin resistant the next day than after a full night, in their liver and in their muscles.
A short week does more. Young men limited to four hours in bed for six nights handled glucose worse than after a week of catching up, and their evening stress hormones were higher.
Timing matters too. Healthy young adults who ate the same dinner close to bedtime, four hours later than usual, had higher blood sugar through the night than when they ate it early.
A shorter eating window may help on its own. Men with prediabetes who ate all their meals within six hours, early in the day, for five weeks became more sensitive to insulin and had lower blood pressure than on a twelve-hour schedule, even though their weight stayed the same.
Set a bedtime that gives you a full night, and keep it for a week.
8. Take the edge off stress
Stress pushes blood sugar up. People with type 2 diabetes who sat a stressful speaking and arithmetic test after a meal had blood sugar 1.5 mmol/L higher than on a calm day, while their cortisol, the main stress hormone, tripled.
On a stressful day, take your ten-minute walk after the next meal and let it do double duty.
9. Add vinegar, and be wary of supplements
Vinegar is an old trick with real evidence behind it. When the tests were pooled, people who had vinegar with a meal had a smaller rise in blood sugar and insulin afterwards than people who ate the meal plain. It seems to work in the stomach: with vinegar added, a starchy meal left the stomach more slowly, so its sugar reached the blood more gradually.
Most supplements sold for blood sugar are marketing. Berberine, a plant compound, is the one with some evidence: across 14 small trials it lowered blood sugar, though the trials were of low quality. It also interacts with several medicines, including some diabetes tablets and drugs used after transplants, so check your medicines against it first.
Dress your salad with vinegar and olive oil, and eat it before the rest of the meal.
Flatten the curve
Blood sugar spikes come from what you eat, the order you eat it in, and what you do afterwards. All three are in your hands at the next meal.
Start with dinner tonight: meat and vegetables first, then a ten-minute walk. How you feel an hour later will tell you more than a yearly snapshot.
Hit a wall every afternoon? 5 Ways to Harness Your Energy and Beat the Afternoon Slump — the sugar crash, the afternoon dip, and the ten minutes that help with both.
Always reaching for something sweet? The Hidden Science of Sugar Cravings — why sugar keeps calling, and how to quiet it.
Know someone who crashes after lunch? Send them this, and take them for a walk after dinner.
Disclaimer: This article is general information. For advice about your own health, talk to a qualified health professional.
Affiliate Disclosure: This article contains affiliate links. As an Amazon Associate, All For Life earns from qualifying purchases, at no extra cost to you. We only link to products we would recommend without the commission.
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