Insulin resistance: the early warning sign that shows up years before diabetes

Written by Amy Fiedler-Kitchen

November is National Diabetes Month, so it’s a good time to talk about the condition that usually comes first. Type 2 diabetes rarely appears overnight. For most people, it’s the end of a long road that starts with insulin resistance, often many years before a diagnosis. The encouraging part is that insulin resistance is common, it’s easy to check for, and it often improves dramatically with the right changes.

According to the CDC, more than 2 in 5 American adults, over 115 million people, have prediabetes, and about 8 in 10 of them don’t know it. Many more have insulin resistance with blood sugar that still looks normal on a routine lab.

What insulin resistance is

Insulin is the hormone that moves sugar from your blood into your cells, where it’s used for energy. Think of it as a key that unlocks the door. With insulin resistance, the locks get sticky. Your cells, especially in your muscles, liver and fat, stop responding well, so your pancreas makes more and more insulin to keep blood sugar in range.

For years, that extra effort works, and your blood sugar can look perfectly normal. But high insulin levels come with a cost. Over time, the pancreas can’t keep up, blood sugar starts to rise into the prediabetes range, and eventually into type 2 diabetes. In one long-term study, people who went on to develop diabetes already had slightly higher fasting blood sugar 13 years before their diagnosis.

Why it matters even before diabetes

Insulin resistance isn’t just a blood sugar problem. It’s closely tied to high blood pressure, high triglycerides, low HDL (good) cholesterol, fatty liver disease, PCOS, sleep apnea and heart disease. It also makes weight harder to lose, especially around the middle, and can leave you hungry, tired and craving carbs even when you’re eating well.

Signs you might notice

Many people have no symptoms at all, which is why testing matters. When there are clues, they often look like this:

  • Weight that settles around your middle. A waist larger than 35 inches for women or 40 inches for men is linked to a higher risk of type 2 diabetes and heart disease.

  • Energy crashes or hunger soon after meals, especially carb-heavy ones, and strong cravings for sweets.

  • Dark, velvety patches of skin on the neck, armpits or groin (called acanthosis nigricans), and skin tags.

  • Irregular periods or PCOS, which are closely linked to insulin resistance.

  • Lab results drifting the wrong way, such as rising triglycerides, low HDL, higher blood pressure or a fatty liver on imaging.

  • A family history of type 2 diabetes or a personal history of gestational diabetes.

For women, perimenopause and menopause can add another layer. As hormones shift, weight tends to move to the middle and blood sugar control can change, which is one reason I look at hormones and metabolism together.

Who should get tested

The American Diabetes Association recommends testing all adults starting at age 35, and earlier for adults with overweight plus another risk factor, such as a family history of diabetes, high blood pressure, PCOS, a history of gestational diabetes or an inactive lifestyle. If your results are normal, testing is usually repeated at least every three years. If you have prediabetes, it should be checked every year.

The labs that tell the story

These are the standard tests, with the ranges the American Diabetes Association uses:

  • A1c (your average blood sugar over about three months): below 5.7% is normal, 5.7% to 6.4% is prediabetes, and 6.5% or higher is diabetes.

  • Fasting glucose: below 100 mg/dL is normal, 100 to 125 is prediabetes, and 126 or higher is diabetes.

  • Two-hour glucose tolerance test: below 140 mg/dL is normal, 140 to 199 is prediabetes, and 200 or higher is diabetes.

Here’s where a closer look helps. “Normal” isn’t always the same as “doing well.” An A1c of 5.6% is technically normal, but if it was 5.2% a few years ago, the trend matters. Insulin resistance can also be present long before glucose rises, because your body is working overtime to keep it normal.

That’s why, depending on your history, I may also look at fasting insulin, your triglyceride-to-HDL ratio, liver enzymes, inflammation markers such as hs-CRP, and your waist measurement. There’s no single agreed-upon cutoff for fasting insulin, so I don’t read any one number in isolation. Together, though, these markers can show the problem early, when it’s easiest to turn around.

What actually works

The best evidence comes from the Diabetes Prevention Program, a landmark study of more than 3,000 adults with prediabetes. People who lost about 7% of their body weight and got 150 minutes of activity a week cut their risk of developing type 2 diabetes by 58% over about three years. Twenty years later, they were still less likely to have diabetes. Here’s what I focus on with patients:

  • Lose a modest amount of weight, if you have extra. A loss of 5% to 7% of your body weight, about 10 to 14 pounds for someone who weighs 200, can make a real difference.

  • Walk after meals. In one study of adults with type 2 diabetes, a 10-minute walk after each meal lowered post-meal blood sugar 12% more than a single 30-minute daily walk, and 22% more after dinner. Even a few minutes of light walking helps.

  • Build muscle. Muscle is where much of the sugar from a meal goes, so strength training two to three times a week improves insulin sensitivity at any age.

  • Eat for steady blood sugar. Mediterranean-style and lower-carbohydrate eating patterns have the strongest evidence for preventing type 2 diabetes. Start meals with protein and vegetables, choose fiber-rich carbs, and limit sugary drinks and refined snacks.

  • Protect your sleep. In one study, a single night of only four hours of sleep made healthy adults measurably insulin resistant. Aim for seven or more hours, and let us know if you snore or wake up tired, since sleep apnea worsens insulin resistance.

  • Manage stress. Stress hormones like cortisol raise blood sugar. Regular movement, time outdoors and good sleep all help.

Some patients find a continuous glucose monitor (CGM) eye-opening. Over-the-counter CGMs are now available for adults who don’t use insulin, and wearing one for a couple of weeks can show exactly how your body responds to specific meals, sleep and stress. It isn’t necessary for everyone, but it can be a powerful motivator.

When medication can help

Lifestyle changes come first, but they aren’t the only tool. For people at higher risk, or when blood sugar keeps climbing despite real effort, medication can make sense. Metformin has been used for decades and lowered the risk of diabetes by 31% in the Diabetes Prevention Program. For people who also need to lose weight, a GLP-1 medication may be an option. You can read more in my article on GLP-1 medications for weight loss.

How we approach insulin resistance at Lovena

  • Screening through primary care. Labs such as an A1c, fasting glucose and cholesterol panel are part of routine primary care, which we bill to insurance. Many plans cover diabetes screening as preventive care.

  • A deeper look through functional medicine. For patients who want to understand the root causes, we look at the bigger picture: insulin, inflammation, hormones, sleep, stress, nutrition and family history.

  • A plan you can actually follow, built around your schedule, your preferences and your goals.

  • Medication when it’s the right fit, including metformin or a GLP-1, with careful monitoring.

  • Follow-up labs to make sure the plan is working, usually every three months at first.

Primary care is billed to insurance. Functional medicine and medical weight loss are cash-pay, and we’ll go over costs before you start.

Know your numbers

If you’ve never had your A1c checked, or you’ve been told your blood sugar is “a little high,” now is the time to take a closer look. Insulin resistance is far easier to reverse than diabetes is to treat. Call or text (602) 894-8398 or book online to schedule a primary care visit. Interested in a root-cause approach? Start with a free 15-minute functional medicine discovery call.

Sources

This article is for general education and isn’t medical advice. Talk with your own provider about your situation.

Amy Fiedler-Kitchen
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GLP-1 medications for weight loss: who they’re for, how they work and what to expect