Plans for Your Body · Blood sugar & insulin
The prediabetes plan
Prediabetes is a warning, not a sentence.
The goal: Prediabetes means years of high insulin have started to show up in your blood sugar. For many people it’s reversible: cut sugar and refined carbs, eat in a window, fast once a week, lift and walk, and retest HbA1c at 4–6 months. In trials, getting back to normal glucose even once cut later diabetes risk by about half.
Most people hear “prediabetes”, get a pamphlet, and are told to come back in a year. A year later it’s diabetes. This plan treats the diagnosis as what it is: a window that’s still open. Measure where you are, lower the insulin that’s driving it, and retest until HbA1c is back where it belongs.
- MeasureHbA1c · fasting glucose · fasting insulin · two-week CGM · waist
- ChangeCut refined carbs · eating window · weekly 36-hour fast · strength, walking, sleep
- RetestHbA1c at 4–6 months, until it’s back to normal
Most people wait for diabetes. This closes the window first.
Not medical advice
Discuss everything here with a medical doctor before acting on it — supplements included. Your doctor has your bloodwork and history. We have neither.
02 Why it matters
The clock is already running.
The default
Watchful waiting. Prediabetes is common enough to be treated as normal, but each year roughly 5–10% of people with it progress to type 2 diabetes. The damage to blood vessels starts before the diagnosis does.
The evidence
In the Diabetes Prevention Program, lifestyle change cut progression to diabetes by 58%, almost twice what the drug tested alongside it managed. People who got their glucose back to normal even once had 56% lower diabetes risk years later.
Knowing why your sugar is creeping up changes how you fix it.
03 How it works
Blood sugar is the last number to break.
Insulin resistance starts years before blood sugar rises. At first the pancreas compensates by making more insulin, so glucose looks normal while insulin climbs. Prediabetes is the point where even the extra insulin can’t keep up. Lower the insulin and, for most people, the sugar follows.
- HbA1c
- Your average blood sugar over about three months. Diabetes Canada calls 6.0–6.4% prediabetes; the US line starts at 5.7%. 6.5% is diabetes.
- Fasting glucose
- Prediabetes is 6.1–6.9 mmol/L in Canada (100–125 mg/dL in the US). A snapshot: useful, but it misses the spikes.
- Fasting insulin
- The early warning. High insulin with normal glucose means you’re compensating, and high insulin keeps the body storing rather than burning. This is the number to move first. Most doctors don’t order it unless asked.
- Beta cells
- The cells in the pancreas that make insulin. DeFronzo’s clamp studies found that people at the upper end of impaired glucose tolerance are already close to maximally insulin resistant and have lost most of their beta-cell function. Prediabetes isn’t early. It’s late in a long process, and the sooner you take the load off, the more function there is left to save.
- Liver and visceral fat
- Fat in and around the liver makes it ignore insulin and keep releasing glucose overnight. It’s often the first fat to go when insulin falls.
- Muscle
- Where most of a meal’s glucose ends up: in DeFronzo’s clamp studies, muscle took up roughly 80% of the glucose insulin cleared, and it’s where insulin resistance shows first. Less muscle, less room. Building it is one of the cheapest fixes there is.
04 The steps
Measure. Lower insulin. Retest at 4–6 months.
Measure · Week 0
Know your starting point.
- HbA1cthe main number
Your diagnosis and your finish line. Get the actual result, not “it’s a bit high”.
- Fasting insulin and glucosemorning, after an overnight fast
Together they give HOMA-IR, a simple insulin-resistance score. Fasting insulin often isn’t covered in Canada. It’s cheap to pay for.
- Continuous glucose monitortwo weeks
A small sensor on your arm for 14 days shows which meals spike you, how high, and for how long. Repeat every 4–6 months to see the trend. For prediabetes, watch how high you go after meals and how long it takes to come back down.
- Waisttape measure
Measure at the belly button. More than half your height points to visceral fat. Cheap, and it moves before the lab numbers do.
- Lipid paneltriglycerides and HDL
High triglycerides and low HDL usually travel with insulin resistance. Your TG/HDL ratio is a free second opinion.
Change the inputs · Months 1–6
Lower insulin every day, and once a week for longer.
- Sugar and refined carbscut hard
Sugar, sweet drinks, juice, white flour and most packaged snacks. The fastest lever on insulin, blood sugar and triglycerides. For prediabetes, this is most of the game: fewer spikes means less insulin needed to handle them.
- Real foodprotein first
Build meals on protein, vegetables and natural fats: fish, meat, eggs, dairy, legumes, nuts. Protein and fibre keep you full and flatten glucose spikes.
- Eating windowdaily, e.g. noon to 8 pm
Eat inside a fixed window and not outside it. Fewer insulin spikes per day, fewer chances to overeat.
- 36-hour fastonce a week
Dinner one day, then only water, black coffee or tea until breakfast two days later. A standard protocol in Dr. Fung’s clinic: long enough for insulin to fall and the body to draw on stored fat. A pinch of salt helps with headaches. Long fasts drain the liver’s sugar stores and give insulin its longest break of the week.
- Trainingstrength 2–3×/week, cardio 150+ min/week
Lift, and walk briskly or cycle most days. Muscle is where most of a meal’s glucose ends up, so more muscle means more room for it. Cardio makes that muscle more sensitive to insulin. A 10–15 minute walk after your biggest meal blunts that meal’s spike. Lifting builds the muscle that soaks up most of your glucose, so pair it with protein, including a solid first meal.
- Sleep7+ hours
One short night measurably worsens insulin sensitivity, blood sugar and appetite the next day. The cheapest part of the protocol, and the most skipped.
- Alcoholnone while fixing the numbers
It goes straight to the liver, raises triglycerides and adds to liver fat. Less is better; none is best while you’re fixing the numbers.
Before you fast
Don’t do extended fasts if you’re on insulin or other diabetes medication, pregnant, breastfeeding, underweight, or have a history of eating disorders, unless your doctor approves.
Supplements · optional, with your doctor’s OK
Four with evidence for blood sugar. Food comes first.
- Psyllium husk~5 g, twice a day, with a full glass of water
A soluble fibre. Always with plenty of water: taken dry, it can choke or block. Taken before meals, it slows how fast carbohydrates reach your blood and blunts the spike.
Find it on Amazon: Psyllium husk - Berberine500 mg, twice a day, with meals
A plant compound studied for blood sugar and lipids; about 1 g a day worked best in pooled trials. Stomach upset is common. It interacts with several medications, adds to the effect of diabetes drugs, and isn’t for pregnancy or breastfeeding. Pooled trials found lower fasting glucose, HbA1c and insulin.
Find it on Amazon: Berberine - Magnesium~300–400 mg a day of elemental magnesium, with food
Lowered blood pressure by about 2 mmHg in pooled trials, and modestly improved blood sugar in people with or at risk of diabetes. Small, but cheap and safe for most. Loose stools are the usual side effect. Avoid with kidney disease, and take it a few hours apart from thyroid pills, osteoporosis pills and some antibiotics. Modestly improved blood-sugar measures in people at risk of diabetes.
Find it on Amazon: Magnesium - Vitamin D31,000–2,000 IU a day, only if a blood test is low
Worth taking to correct a low level, not as insurance. In a trial of almost 26,000 adults, 2,000 IU a day didn’t prevent heart attacks or cancer. In prediabetes, pooled trials found about 15% fewer people went on to diabetes, mostly at higher doses. Stay at or under 4,000 IU a day unless your doctor says otherwise: too much raises blood calcium. Only if your level is low. Pooled trials found about 15% fewer people with prediabetes progressed to diabetes.
Find it on Amazon: Vitamin D3
Retest · Months 4–6
Back to normal? Keep going.
- HbA1c and fasting insulinsame lab
Compare with week 0. HbA1c reflects about three months, so retesting earlier undersells your progress.
- Another CGMtwo weeks
Fewer, smaller spikes, coming down faster.
- If you’re back to normalmaintenance
Keep the eating window and the training; the weekly fast can become occasional. Retest yearly. Prediabetes comes back if the old habits do.
- If the numbers won’t moveyour doctor
Take the before-and-after numbers to your doctor. Whether you need medication is their call. Needing it isn’t failure. If HbA1c reaches 6.5% at any point, that’s diabetes, and a different conversation.
05 The rules
Short list. No exceptions.
Choose
- Protein and vegetables at every meal
- A fixed eating window, and one 36-hour fast a week
- A walk after your biggest meal
- Strength training 2–3 times a week, and 7+ hours of sleep
Avoid
- Sugar, sweet drinks, juice and white flour
- Snacking outside your window
- Ultra-processed food sold as “diabetic” or “low-fat”
- Waiting a year to retest
Non-negotiables
- Get your HbA1c back under 6.0% (5.7% by US standards).
- Talk to a medical doctor before you fast or start a supplement.
- If you smoke, quit. It worsens insulin resistance, and quitting cuts the extra heart risk it adds, fast at first, though that risk stays above a never-smoker’s for years.
- Retest at 4–6 months, every time.
06 Checkpoints
What to track, and what good looks like.
Your doctor confirms the diagnosis and your targets. These are the standard thresholds.
| What | Target | How and when |
|---|---|---|
| HbA1c | <6.0% (Canada) · <5.7% (US) | Every 4–6 months until normal, then yearly. 6.5% or higher is diabetes. |
| Fasting glucose | <6.1 mmol/L (Canada) · <5.6 mmol/L, 100 mg/dL (US) | Morning blood test after an overnight fast. |
| HOMA-IR | Under ~1.0 is ideal; over ~2.5 suggests insulin resistance | Fasting glucose (mmol/L) × fasting insulin (µU/mL) ÷ 22.5. |
| 1-hour glucose (glucose tolerance test) | <8.6 mmol/L (155 mg/dL) | 75 g glucose drink, blood drawn at one hour. DeFronzo’s group showed this cut-off predicts diabetes better than fasting glucose; the International Diabetes Federation backed it in 2024. Not routine in Canada yet, so ask. |
| CGM readings | Mostly 3.9–7.8 mmol/L (70–140 mg/dL), back down within 2 hours of a meal | Two weeks, every 4–6 months. |
| Waist-to-height | <0.5 | Waist at the belly button divided by height, same units. |
| TG/HDL ratio | <0.9 (mmol/L) · <2 (mg/dL) | From your lipid panel. |
Converted values are rounded. Canada and the US draw the prediabetes line in different places: use your lab’s units and your doctor’s targets.
07 Where experts disagree
Where the experts don’t agree.
Everyone agrees lifestyle change lowers the odds of going on to diabetes. The arguments are about why it works, whether drugs belong in the picture early, and whether the label helps.
Is it the carbs, or the weight?
Insulin first: Fung
Refined carbohydrates and constant eating keep insulin high. Lower insulin with carb restriction and fasting, and blood sugar often follows before much weight comes off.
Weight first: Taylor
Fat in the liver and pancreas is the driver. Lose enough of it, by any diet, and blood sugar normalises. In his DiRECT trial, a low-calorie diet put nearly half of people with type 2 diabetes into remission at one year.
Our read They meet in the middle: cutting refined carbs and fasting are among the easiest ways to lose liver fat. Use the method you’ll sustain, and let the numbers judge it.
Is fasting better than just eating less?
Fasting: Fung
Fasting lowers insulin in a way that grazing on fewer calories doesn’t, and pushes the body into its fat stores, liver fat included.
Trialists: Liu et al.
In a 12-month trial, time-restricted eating plus calorie restriction did no better for weight or metabolic markers than calorie restriction alone.
Our read For blood sugar, total intake matters most. Fasting is a way to get there that many people find easier than counting.
Is “prediabetes” even a useful diagnosis?
Sceptics: Yudkin, Montori
The label turns millions of people into patients, many of whom would never get diabetes, and opens the door to drugs they don’t need.
Act now: Knowler and the DPP
In the Diabetes Prevention Program, people with raised glucose who changed how they ate and moved were 58% less likely to develop diabetes over about three years. Metformin managed 31%. The window is real, and lifestyle uses it best.
Our read The sceptics are right about labels and drugs; the trials are right about lifestyle. The fix that works has no side effects, so the warning is worth acting on.
Lifestyle alone, or a drug early too?
Treat early: DeFronzo
By the time glucose rises, much of the beta-cell function is gone, so protect what’s left. In his ACT NOW trial, pioglitazone cut progression from impaired glucose tolerance to diabetes by 72%, and 48% returned to normal glucose tolerance versus 28% on placebo.
Lifestyle first: Knowler and the DPP
Lifestyle change beat metformin, carries no drug side effects and helps weight and blood pressure too. Pioglitazone came with weight gain and swelling, and later analysis found its protection faded once people stopped it.
Our read Start with lifestyle: it works, and it’s free. If your numbers keep climbing despite real effort, DeFronzo’s point stands, and whether a drug belongs in the plan is a question for your doctor.
08 Limits
What this plan won’t fix.
Some of it is genetic
Family history and ethnicity change how much your body can handle before blood sugar rises. People of South Asian, Indigenous, African and Hispanic descent tend to cross the line at lower weights. You may have to work harder for the same number.
It comes back
Prediabetes isn’t cured; it’s in remission while the habits hold. Go back to the old diet and the numbers go back too.
Some medications raise blood sugar
Steroids and several other drugs push glucose up. If you take one, your doctor needs to be part of this.
The plan lowers the insulin. It doesn’t change your genes or your history.
09 Resources
Worth your time.
The Diabetes Code
Fung’s case for treating type 2 diabetes and prediabetes with diet and fasting rather than ever more insulin.
The Obesity Code
Why insulin, not calories, sets your weight and your blood sugar.
From the triumvirate to the ominous octet: a new paradigm for the treatment of type 2 diabetes
The standard account of how insulin resistance and beta-cell failure build up years before diabetes. Technical, but the opening pages are readable.
Definition, classification and diagnosis of diabetes, prediabetes and metabolic syndrome
How prediabetes is defined and diagnosed in Canada.
Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin
The Diabetes Prevention Program. The trial behind most of what anyone can honestly promise about prediabetes.
10 Questions
Questions, answered plainly.
Can prediabetes be reversed?
Often, but not for everyone. In the Diabetes Prevention Program, lifestyle change cut progression to diabetes by 58%, and people who got back to normal glucose even once had 56% lower risk later. Some people still progress despite real effort; genes and how much beta-cell function is left both matter. Where it does reverse, it stays that way only as long as the habits do.
How long does it take to reverse prediabetes?
Blood sugar and insulin improve within weeks. HbA1c reflects about three months, so retest at 4–6 months to see the real change.
What should I eat with prediabetes?
Protein, vegetables and natural fats, and little sugar or refined flour. The fewer and smaller your glucose spikes, the less insulin you need.
Is fruit OK?
Whole fruit in modest amounts is fine for most people. Juice and dried fruit are sugar with better marketing. Your CGM will show you which fruit spikes you.
Do I need to lose weight?
If you carry excess weight, especially around the waist, losing it is one of the strongest levers. Some people get back to normal glucose before losing much, because insulin falls first.
Is intermittent fasting safe with prediabetes?
For most people who take no glucose-lowering medication, yes, with a doctor’s OK. If you take any, don’t fast until your doctor has adjusted it.
11 Sources
Where this comes from.
Experts drawn on
- Ralph DeFronzo, MD — Professor of medicine and chief of the diabetes division, UT Health San Antonio. Pioneered the insulin clamp; led the ACT NOW prevention trial; author of the ominous octet model.
- William Knowler, MD, DrPH — Diabetes epidemiologist, long at the US National Institute of Diabetes and Digestive and Kidney Diseases. First author of the Diabetes Prevention Program results.
- Roy Taylor, MD — Professor of medicine and metabolism, Newcastle University. Led the DiRECT remission trial.
- Jason Fung, MD — Nephrologist, Toronto. Author of The Diabetes Code and The Obesity Code.
- John Yudkin, MD, and Victor Montori, MD — Diabetes researchers (UCL, Mayo Clinic). Critics of prediabetes as a diagnosis.
Sources
- Definition, classification and diagnosis of diabetes, prediabetes and metabolic syndrome. Diabetes Canada Clinical Practice Guidelines.
- Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin (Diabetes Prevention Program). New England Journal of Medicine, 2002.
- Effect of regression from prediabetes to normal glucose regulation on long-term reduction in diabetes risk. The Lancet, 2012.
- Prediabetes: a high-risk state for diabetes development. The Lancet, 2012.
- Primary care-led weight management for remission of type 2 diabetes (DiRECT). The Lancet, 2018.
- Calorie restriction with or without time-restricted eating in weight loss. New England Journal of Medicine, 2022.
- The epidemic of pre-diabetes: the medicine and the politics. BMJ, 2014.
- Psyllium fiber improves glycemic control proportional to loss of glycemic control: a meta-analysis. American Journal of Clinical Nutrition, 2015.
- Effect of berberine on cardiovascular risk factors: systematic review and dose-response meta-analysis. Frontiers in Nutrition, 2022.
- Oral magnesium supplementation for treating glucose metabolism parameters in people with or at risk of diabetes: a systematic review and meta-analysis of double-blind randomized controlled trials. Nutrients, 2021.
- Vitamin D and risk for type 2 diabetes in people with prediabetes: a systematic review and meta-analysis of individual participant data from 3 randomized clinical trials. Annals of Internal Medicine, 2023.
- From the triumvirate to the ominous octet: a new paradigm for the treatment of type 2 diabetes mellitus (Banting Lecture). Diabetes, 2009.
- Skeletal muscle insulin resistance is the primary defect in type 2 diabetes. Diabetes Care, 2009.
- Pioglitazone for diabetes prevention in impaired glucose tolerance (ACT NOW). New England Journal of Medicine, 2011.
- Diabetes incidence and glucose tolerance after termination of pioglitazone therapy: results from ACT NOW. Journal of Clinical Endocrinology & Metabolism, 2016.
- One-hour plasma glucose concentration and the metabolic syndrome identify subjects at high risk for future type 2 diabetes. Diabetes Care, 2008.
- International Diabetes Federation position statement on the 1-hour post-load plasma glucose for the diagnosis of intermediate hyperglycaemia and type 2 diabetes. Diabetes Research and Clinical Practice, 2024.
- Association of smoking cessation with subsequent risk of cardiovascular disease. JAMA, 2019.
Not medical advice
Discuss everything here with a medical doctor before acting on it — supplements included. Your doctor has your bloodwork and history. We have neither.