If your fasting blood sugar and hemoglobin A1c are normal, you may assume your glucose metabolism is working just fine. But that’s not always the case. In fact, the metabolic changes that eventually lead to prediabetes can begin years—sometimes a decade or longer—before your blood sugar officially crosses into the prediabetic range.
If you’re gaining weight around your middle, craving carbohydrates, crashing in the afternoon, feeling hungry two hours after eating, or wondering why the same strategies that helped you lose weight ten years ago now barely make the scale blink, your body may be telling you it’s time to dig a little deeper.
The Evolution of Insulin Resistance
When you eat carbohydrates, they're broken down into glucose, which then enters your bloodstream. In response, your pancreas releases insulin—a hormone that helps move glucose out of your bloodstream and into your cells, where it can be used for energy or stored for later.
As long as your cells pay attention to insulin’s commands, this system works beautifully. But if certain triggers show up uninvited—like a diet that’s less than stellar, hormone imbalances, sleep deprivation, or an ever-expanding waistline—your cells can become a bit distracted and begin ignoring insulin’s message. This is called insulin resistance.
In the early stages, your pancreas recognizes that your cells aren't responding as well as they should, so it cranks out more insulin to get the message through. And for a while, that compensatory action works. Your insulin may be climbing while your glucose remains perfectly respectable on your routine labs.
Over time, however, the beta cells in your pancreas—the cells responsible for producing insulin—may no longer be able to keep up with the increased demand. Insulin production eventually becomes insufficient to compensate for the resistance, and glucose begins to rise. That's when those once “normal” fasting glucose and A1c levels may start inching toward the prediabetic range.
How Insulin Resistance Packs on the Pounds
As is true for insulin’s hormonal cousins, it doesn’t just have one job. In addition to regulating blood sugar, it’s also an important energy-storage hormone. When insulin levels stay elevated, your body receives the memo to store energy—which means fat cells don’t have to offer up their stores to keep your metabolism humming.
And insulin resistance rarely operates in isolation. It can become tangled up with many of the same metabolic changes affecting women over 40, including shifts in estrogen, increasing abdominal fat, chronic stress, poor sleep, and loss of muscle mass. Each can influence insulin sensitivity, while worsening insulin resistance can make an already complicated metabolic picture even messier.
Your Body May Be Leaving Breadcrumbs
Insulin resistance doesn't always cause obvious symptoms, which is one reason it can be easy to miss. But some women notice patterns such as:
- Increasing weight around the abdomen
- Difficulty losing weight despite reasonable efforts
- Strong carbohydrate or sugar cravings
- Feeling hungry soon after eating
- Fatigue or sleepiness after meals
- Afternoon energy crashes
- Elevated triglycerides or low HDL cholesterol
- Rising blood pressure
- Skin tags or darkened, velvety skin in body folds
None of these symptoms proves you have insulin resistance, they're simply clues that should prompt you to investigate further.
Why Women Over 40 May Become More Vulnerable
Insulin resistance can become particularly problematic during perimenopause and menopause. As estrogen levels fluctuate and eventually decline, women tend to experience changes in body composition, including an increased tendency to store fat around their midsections.
Aging itself often brings with it loss of muscle mass, reduced activity, poorer sleep, and other changes that can reduce insulin sensitivity. Add chronic stress, years of inadequate sleep, a highly processed diet, and less physical activity, and your metabolism can eventually find it difficult to keep up.
How to Catch Trouble Before It Shows Up
Your fasting glucose is a snapshot of the amount of sugar in your bloodstream after you've gone without food—usually for at least 8 to 10 hours. A hemoglobin A1C provides broader information because it estimates your average blood glucose over roughly the previous two to three months. Both can help identify prediabetes and diabetes, but they’re not perfect.
This is why I prefer looking at the bigger metabolic picture, especially in women who are at increased risk. I also check a fasting insulin level because it can tell me something a fasting glucose alone can't: how much insulin your pancreas is making to keep your fasting glucose where it is. If your glucose is still normal but your insulin is elevated, your pancreas may already be working overtime to compensate for insulin resistance. I can also use fasting insulin along with fasting glucose to calculate HOMA-IR, another estimate of insulin resistance.
But as you learned previously, if insulin resistance progresses far enough, insulin production can eventually decline. That's when a fasting insulin level can become misleading. If the numbers don't seem to fit the overall metabolic picture, I order a C-peptide level. C-peptide is released along with insulin, so measuring it provides another way to assess how much insulin your pancreas is making. If C-peptide is high, it suggests that the pancreas is still pumping out plenty of insulin. But if C-peptide is low despite a high fasting glucose, it’s usually a sign that insulin production is beginning to fall short.
Your triglycerides, HDL cholesterol, blood pressure, waist circumference, family history, and changes in these measurements over time can provide additional clues.
Being Proactive is the Key to Prevention
Insulin sensitivity can often improve substantially with lifestyle changes alone. Here are some simple things you can do to keep your metabolism happy and your fat cells pumping out their goods:
- Move. Regular movement helps your muscles take up and use glucose more efficiently. Even something as simple as walking after meals can help.
- Resistance training. Your muscles are one of the major places your body puts glucose to work. The more muscle mass you have—and the more you use it—the better equipped your body is to clear glucose from your bloodstream and improve insulin sensitivity.
- Eat enough protein. A reasonable general target for many women over 40 is around 1.0–1.2 g/kg of body weight per day, with higher amounts sometimes appropriate depending on activity level, health, and goals.
- Eat clean. Cut out the crap, increase your fiber, and eat your veggies. This helps to keep glucose and insulin from riding a roller coaster all day.
- Get adequate sleep. Your metabolism gets very cranky when it’s sleep deprived, and chronic sleep deprivation can reduce insulin sensitivity and eventually repay the favor by increasing your risk of insulin resistance.
- Reduce your stress. I know this is easier said than done. But cortisol, glucose, and insulin are closely connected. Cortisol helps make more glucose available when your body needs energy, so when stress keeps cortisol elevated, glucose regulation can become more challenging and insulin resistance can worsen over time.
If you’re in the throes of perimenopause or have officially graduated into menopause, hormone replacement therapy may also be worth discussing with your practitioner. Estrogen influences insulin sensitivity and body-fat distribution, and the hormonal changes of menopause can contribute to the metabolic shift we've been discussing. HRT isn't a treatment for insulin resistance or a weight-loss medication, but for the right woman, restoring estrogen may have favorable effects on glucose metabolism as part of the bigger picture.
The Bottom Line
Insulin resistance can develop gradually, and your body may compensate for years before your blood glucose finally crosses into the prediabetic range. Looking at your symptoms, family history, waist circumference, blood pressure, lipid patterns, fasting insulin when appropriate, and trends in your laboratory results can provide a much more complete picture of your glucose control and overall risk.
If you're struggling with stubborn weight gain despite doing many of the “right” things, don't automatically assume you need to eat less or exercise more. Your body may be telling you there’s more to your “normal” fasting glucose and HBA1C than meets the eye.
You learn much more about insulin resistance and how other hormone imbalances contribute to weight gain in my Weight Loss After 40 series. Book III is in the works!