A family physician’s guide for type 2 diabetes and prediabetes
What actually lowers your A1c, and what doesn’t.
Your A1c by the Numbers: How Food, Exercise, and Supplements* Affect Your Blood Sugar: The Non-Drug Side of Diabetes Care
Every food, habit and supplement gets a plain grade and a real number. Then a 90-day plan puts them in order.
*And no, I don’t sell supplements. — Dr. Ryan Kasky, DO
Paperback, 7 x 10 in · 240 pages · Sources for every number in the notes
Real numbers, plain language
Every number says what it measures.
Your feed promises miracles. Your doctor has 15 minutes. The book fills the gap with what the trials actually found.
~0.6% lower A1c
from moving about 150 minutes a week, mostly brisk walking.
Measures: A1c, across 127 trials
43 mg/dL
lower blood sugar one hour after the same meal, just by eating vegetables and protein first and carbs last.
Measures: the after-meal spike
58% fewer cases
of new type 2 diabetes in people with prediabetes who joined the Diabetes Prevention Program’s lifestyle program.
Measures: new diabetes over about 3 years
A preview of the scoreboard
Tap a habit. See its priority and its number.
Eight examples from the book’s full ranking. The book covers more than 60.
Move about 150 minutes a week
In a review of 127 exercise trials, most of the A1c benefit came by about 150 minutes a week of brisk walking. Measures A1c, your average blood sugar over about 3 months.
Get diabetes education
In 19 trials, self-management programs built around the patient lowered A1c. Medicare covers diabetes classes and dietitian visits if you qualify.
Cut sugary drinks
In studies that followed people for years, each daily sugary drink was linked to about 18% more risk of type 2 diabetes. A link, not proof of cause.
Eat vegetables and protein first, carbs last
Same meal, same amounts, just a different order: blood sugar about 43 mg/dL lower one hour after eating. Measures the after-meal spike, not A1c.
Psyllium fiber, 10 g a day or more
Across 19 trials. Take it with a full glass of water and apart from your pills.
Berberine
Across 37 studies.
Caution: It changes how your body handles many common medicines. Show your pharmacist your list first.
Cinnamon pills
One review found no effect, another a drop it couldn’t trust, and the ADA does not recommend it for blood sugar. Fine as a spice.
Ice baths, alkaline water, “GLP-1 drops”
Chapter 26 checks 15 popular claims against the research. None of these belongs in a blood-sugar plan.
Bars show the average A1c drop in the reviews (longer bar = bigger drop). Each number comes from a different set of studies, so they don’t add up. Your results will vary.
Look inside
Built to be used, not just read.
Tap a page to enlarge it. Want more? Use Amazon’s “Look Inside” on the book page, or read the free articles.
The grading system
Six grades. One question each time: what does the evidence show?
Unless the book says otherwise, every grade is about blood sugar and diabetes: after-meal spikes, A1c or your chance of getting diabetes. Safety gets its own badge.
Good studies in people show a real effect, big enough to matter.
A real signal, but the trials are small, few or inconsistent.
Not tested properly in people. Mice and lab dishes don’t count.
Tested in people and didn’t help, or the guidelines say skip it.
Might raise blood sugar or diabetes risk, but it isn’t proven.
Clear harm for blood sugar. Not one bite, but not a daily habit either.
The 90-day plan
One change about every two weeks.
Diet first, then exercise, then supplements. Start everything on Monday and Friday usually wins, so the plan goes one step at a time.
Free printable
Your Daily 8
Eight small habits, one box a day. No counting, no weighing, no perfect days. Start with the box you check least.
Letter size. No email, no signup. Print a fresh one each week.
Your Daily 8
- Skipped sugary drinks
- Walked 10–15 min after a meal
- Made half my plate vegetables
- Ate my carbs last
- Had a fiber food
- Got up every 30 minutes
- Slept 7+ hours
- Did strength exercise
Questions
Before you buy
Is this book a treatment plan?
No. It’s education to use alongside your care. It explains what the research shows so you and your doctor can decide what fits you.
Should I stop or change my diabetes medicine?
No. Never stop or change a medicine on your own. The book has a whole chapter on diabetes medicines and why they matter, and a safety chapter for anyone on insulin or a sulfonylurea pill.
Does it promise to cure or reverse diabetes?
No. Type 2 diabetes is managed, not cured. Some people get their A1c below the diabetes range without medicine, and the book explains what that really means and why it’s still management.
Why cover supplements if you don’t sell them?
Because patients ask about them every week. Every supplement gets the same test as everything else: does it work, how much, and is it safe? No supplement earned the top grade for lowering blood sugar.
Who is it for?
Adults with type 2 diabetes or prediabetes, and the family members who help them. It is not for type 1 diabetes, gestational diabetes or diabetes during pregnancy.
Do I need a glucose meter?
No. Your A1c, checked with your doctor every 3 months, tells you most of what you need. If you have a meter or a CGM, the book has optional experiments you can try.
Is it hard to read?
It’s written in plain language, with the deeper science in skippable boxes. Every chapter ends with a four-sentence summary.
Is the Daily 8 really free?
Yes. No email, no signup, no cookies. Print it and put it on the fridge.
From the book
Short reads, real numbers
Apple cider vinegar for blood sugar: meals, pills and gummies
Does apple cider vinegar lower blood sugar? Vinegar with meals blunts the spike; pills and gummies are barely tested. Dr. Ryan Kasky, DO on the evidence.
Berberine for blood sugar: how much it lowers A1c, and the medicine catch
How much does berberine lower A1c? About 0.6% across 37 studies, but it can make other medicines too strong. Dr. Ryan Kasky, DO explains the catch.
Does cinnamon lower blood sugar? What the studies actually show
Does cinnamon lower blood sugar? Dr. Ryan Kasky, DO reviews the trials: reviews disagree, the ADA says no, and cassia carries a liver caution.
Eat your carbs last: the free trick that lowers blood sugar spikes
Eating vegetables and protein before carbs lowered 1-hour blood sugar about 43 mg/dL in type 2 diabetes. How to do it, why it works, and safety notes.
Is fruit bad for diabetes? Whole fruit vs. juice
Is fruit bad for diabetes? Trials say whole fruit does not raise A1c, but juice spikes blood sugar like soda. Grades and real numbers from Dr. Kasky.
Walking after meals: when, how long, and how much it lowers blood sugar
How long to walk after eating and when to start: a 10-15 minute walk soon after meals lowers blood sugar spikes. Real study numbers from Dr. Ryan Kasky.
Updates and corrections
Research changes. So will this page.
When a new study changes a number or a grade in the book, or a reader finds a mistake, it will be listed here with the date.
No updates yet. First edition, 2026.
The author
Written by a family physician, not a supplement company.
Dr. Ryan Kasky, DO, takes care of people with type 2 diabetes and prediabetes. He wrote this book because a 15-minute visit is rarely enough time for these questions.