Blood Sugar Spikes Are Normal. Here's How to Reverse Prediabetes
A bowl of oatmeal and a glucose graph climbing to the right. You've seen that post. A rise after eating is what a healthy body does, and insulin brings it back down. The number worth watching is your baseline, the fasting level you wake up with, and whether it creeps higher across months. What moves that baseline is a short list of basics: balanced meals, strength training, walks after eating and enough sleep.
I covered this on Talking Nutrition, episode 222, with my friend Caitlin Jones, a functional nutritionist who lives near Lake Tahoe. Her own fasting blood sugar once sat in the 140s, measured in mg/dL (about 7.8 mmol/L). Below is what I took from it.
Is a Blood Sugar Spike After Oatmeal Actually a Problem?
Those posts film one food on its own, show the line going up and invite you to be alarmed. Real meals come with company. I said it to Caitlin on the show: "No one eats white rice by itself. With a protein, with some fibre, with some fats, there's a whole different story." Add eggs to that oatmeal and the graph looks different, which the clip rarely shows.
A glucose monitor is a useful tool, and for someone with a diagnosis working alongside a doctor it can teach a lot. My issue is one bowl of oatmeal and a scary caption. Marketing villainised low fat, then sugar, and I think fibre is next.
What Does Blood Sugar Do All Day?
Here is blood sugar 101 in plain English. You eat, glucose enters your blood, your pancreas releases insulin, and insulin pulls the level back down. Caitlin described it like this:
As you eat, your blood sugar increases, insulin is produced, brings back down that spike, and then it brings you back to your maintenance and your middle level.
Her picture of the problem: eat in an unbalanced way, mostly carbohydrate, take a big rise, and insulin can struggle to keep up. The level settles higher than where it began, the next meal starts from that higher ground, and across months the baseline climbs. Stress pushes the same direction. A busy adult can see a fasting number lift from stress alone, so if that sounds like you, start with managing stress.
On numbers, Caitlin's ideal fasting range is 70 to 85 mg/dL (3.9 to 4.7 mmol/L). That is her view, and she finds the usual cutoff a little generous. Most labs call anything up to 99 mg/dL (5.5 mmol/L) normal and 100 to 125 (5.6 to 6.9 mmol/L) prediabetes. Your doctor is the right person to read your report with you.
One boundary. Type 1 diabetes is autoimmune and a different conversation, so everything here covers prediabetes and type 2, where lifestyle drives most of the picture.
What Happened to Caitlin's Blood Sugar?
Going on four years ago, Caitlin was diagnosed pre-diabetic. She was powerlifting for an hour a session, four to five days a week, and hitting her macros to a T. Her fasting blood sugar kept rising until it reached the 140s.
Her coach wanted her strong, so her carbs went up in jumps of 20 to 30 grams, until her highest day hit 370 grams. Seeing a number like that, she told me, made her think she could eat whatever she wanted. Her take now: "when you're mainlining Swedish fish through a workout, something's a little bit wrong there."
It felt like under-eating. She was tired, and her sleep and recovery suffered. Eating too much produces the same feelings, she explained, because the body is digesting so much at once. "The output was not matching the input at all," she said.
I know that trap from the coaching side. I was big on flexible dieting and still use a version of it, 80/20 whole foods, or 90/10 in a fat loss season. In my early coaching years I communicated it badly. People heard the word flexible and stopped listening, when we always led with whole foods.
Why Do So Many Women Eat Too Much Protein and Too Few Carbs?
Caitlin sees the reverse of her own story in clients today. "What's funny is now the protein craze is huge. And so they come in eating way more protein than they ever need." It arrives through fortified food like protein oatmeal and protein chips. Protein powder is the one product she keeps.
I see the carbohydrate half. I coach mostly women, and getting someone to maintenance and past 200 grams of carbs a day can feel like a mountain of food. My guide to maintenance calories is where I'd begin, and tracking macros for beginners shows how to see your meals in grams. I like protein too, and high-protein foods are part of how I coach. The question is amount and balance.
If you'd rather hear Caitlin tell it herself, the full episode is below. Keep reading for the part most people get wrong.
Can You Have Prediabetes and Not Look It?
Within the last year, a client came to Caitlin and said she was pre-diabetic. She is stick thin, and her doctor doubted it. She tested her sugars for a week, and sure enough, the client was right.
Caitlin recalled the doctor's reasoning as "you don't look like it." Her answer: "well, it can." If you've been handed a "borderline, keep an eye on it" result, your body shape tells you nothing either way. A fasted test and your doctor do.
How Do You Reverse Prediabetes? Caitlin's Steps and Her Take on GLP-1
Caitlin's word for her own result is reversed. In my words, she pushed her blood sugar back into a normal range. At 5 foot 2 she weighed 192 pounds (87 kg), and her body hurt on bike rides and hikes. She had years of coaching behind her, so she moved a few dials:
She ate in a calorie deficit, a little less than before.
She lowered her carbs.
She held her protein where it was.
She left fats alone.
She walked outside after meals, the kind of daily movement that adds up.
She lifted and trained exactly as before.
That is one woman's story, shared for education. Timelines vary, so I'd rather give you the order of operations than a calendar.
Caitlin was open about the other part. She also used a GLP-1, semaglutide, at a very low dose for eight months, then weaned herself off, kept the result and gained muscle on top.
That was a tool that I used to help make the process a tiny bit faster because I had the basics nailed.
I told her what I think. There is a time and place for medication, and since she had everything dialled in, the drug sped up something she could have done without it. It gets slippery when people take the drug and skip the food and lifestyle work. Some of the people who now come to Caitlin stopped cold and gained the weight back, and some get sick when they try the drug again. Whether a medication belongs in your plan is a decision between you and your doctor.
I use myself as the example here. When I was overweight, this was the honest picture:
I ate like crap and I smoked and I drank and I was on the couch playing video games. I didn't lift weights.
In 2012 I tried a fat burner on top of all that. It left every one of those habits exactly where they were. The habits were the cause, so the habits were the work.
What Does a Prediabetes Diet Start With?
A food log. Caitlin leads with three to five days of what a client eats, then a conversation to confirm that was everything. The coffee gets a question. Five pumps of sugar? Creamer? Dressings and cooking fats add up too. People under-report more often than not, and the gap tends to hide in fat, which is calorie dense.
Labs come second. Her clients arrive with an A1C from their GP, a three-month average of blood sugar that she calls the bare minimum, and she adds fasted insulin. If only fasting blood sugar has risen while insulin still looks fine, that is a whole lot easier to fix.
Then comes muscle. Caitlin says muscle mass helps you be more insulin sensitive, because your muscles give that sugar somewhere to go. That is why her list keeps the lifting, and why keeping your muscle while you cut deserves attention. She summed up the whole approach in one line: "It is the unsexiest thing ever, but it works."
What Is the Hardest Part of Changing Your Blood Sugar?
Knowing what to do takes a paragraph. Doing it long enough to build new habits is a different job, which is why coaches exist. For Caitlin the hardest part is the habits clients never knew were habits, like a morning coffee, or a breakfast that fails to keep you full until lunch. She also has clients eat for something: an event, a date on the calendar. When they reach it, she shows them everything they did to get there.
The hunger part is mine. I'd seen a post the day we recorded that I agreed with, and I said it on the show: "When we're hungry, we can also just be a little hungry without that having to mean I've got to eat something right now. It's actually a normal thing, being a little bit hungry sometimes."
Early on, Caitlin says, clients cannot yet trust their hunger and fullness cues after years of dieting ups and downs. People love to bring up intuitive eating here, and her answer is maybe someday, once they are at maintenance and the cues have settled. Her name for it:
I call intuitive eating the PhD of eating. That is what we strive for.
Caitlin and I covered more than I could fit into one post.
Talking Nutrition is my podcast. Each episode I sit down with a peer or a specialist, and we go through their topic in plain English.