Insulin Resistance Symptoms: The Early Signs, and What They Are Not

Type “insulin resistance symptoms” into a search bar and you get lists. Fatigue. Brain fog. The three o’clock crash. Sugar cravings. The federal agencies that actually define the condition publish none of that. NIDDK, the NIH institute responsible for diabetes, states that people with insulin resistance and prediabetes usually have no symptoms, and the CDC says there are usually no signs when you have prediabetes, which is why an estimated 8 in 10 people who have it do not know. The one visible sign with real documentation behind it is acanthosis nigricans, patches of darker, thickened, velvety skin in the folds of the neck, the armpits or the groin. Everything else is settled by a blood test, an A1C, a fasting plasma glucose, or an oral glucose tolerance test, and not by how you feel.

What the agencies say about insulin resistance symptoms

That is a short and unsatisfying list, which is probably why so few articles lead with it. NIDDK’s own page notes that some people may have symptoms of diabetes itself, the later condition rather than the earlier one, but it presents no symptom list for insulin resistance. No federal page describes an energy crash or a craving pattern as a recognized early sign. If you find one in a search result, check whose name is on it.

The reason this matters is arithmetic. CDC puts the number of American adults with prediabetes at about 115 million, more than 2 in 5, and its National Diabetes Statistics Report gives 115.2 million adults aged 18 and older. Among adults 65 and older, 31.3 million have prediabetes, which is 52.1% of that age group. Separately, 40.1 million people have diagnosed or undiagnosed diabetes, 12.0% of the population, and 27.6% of adults with diabetes have not been diagnosed. A condition that quiet, spread that wide, is not going to announce itself on a Tuesday afternoon.

So the useful question is not what insulin resistance feels like. It is what it looks like on a lab slip, and who is supposed to be checking.

The one sign that is genuinely documented

Acanthosis nigricans is the exception. MedlinePlus, the NIH National Library of Medicine’s encyclopedia, describes it as a skin disorder in which there is darker, thick, velvety skin in body folds and creases, typically in the armpits, the groin and the neck folds. It lists insulin resistance among the causes. It usually develops gradually and without discomfort, which is exactly why people can live with it for years without mentioning it to anyone.

The American Academy of Dermatology adds detail. The affected skin is brown or black, velvety and thicker than the skin around it, and skin tags often appear in the same areas. Obesity is the most common cause, and the AAD notes that studies show obese children and adults who have the condition often see their skin clear after losing a significant amount of weight. It can also be a sign of prediabetes or diabetes, which is why a dermatologist is sometimes the first person to raise blood sugar with a patient who came in about their neck.

Two cautions travel with that. MedlinePlus warns that if the condition develops rapidly and in a widespread fashion, an association with cancer should be considered, so a sudden onset is a reason to be seen rather than a reason to keep reading. MedlinePlus also notes it often disappears if the cause can be found and treated, which cuts both ways: the skin is a marker, not the disease.

And nobody publishes a figure for how often these skin changes show up in people with insulin resistance. Not MedlinePlus, not the AAD. So the absence of a velvety patch tells you nothing at all.

How it actually gets found

This is the part that surprises people who arrive planning to request a test. NIDDK states that health care professionals may not test for insulin resistance, and that the test for insulin resistance is primarily used only for research studies. There is no routine clinical measurement of the thing itself. What gets measured is what it does to blood sugar.

Prediabetes is diagnosed with one of three tests. An A1C between 5.7% and 6.4%. A fasting plasma glucose between 100 and 125 mg/dL. Or an oral glucose tolerance test with a two hour value between 140 and 199 mg/dL. The American Diabetes Association’s public diagnosis page gives identical cutpoints and adds the diabetes thresholds sitting above them: an A1C of 6.5% or higher, a fasting plasma glucose of 126 mg/dL or higher, a tolerance test result of 200 mg/dL or higher. The tolerance test is the one that watches a curve rather than a single point, and if the shape of that curve is unfamiliar, we walk through what happens to blood sugar after you eat separately.

Screening is where the silence gets acknowledged out loud. The US Preventive Services Task Force recommends, at Grade B, screening for prediabetes and type 2 diabetes in asymptomatic adults aged 35 to 70 years who have overweight or obesity, defined as a BMI of 25 or higher and of 30 or higher respectively. In 2021 the Task Force lowered the starting age from 40 to 35. Read the wording again. The recommendation is written for nonpregnant adults in primary care with no symptoms of diabetes, and it exists precisely because waiting for a symptom does not work.

The measurements that put someone into that conversation are ordinary ones. The NIH National Heart, Lung, and Blood Institute counts a waist circumference of more than 35 inches for women or more than 40 inches for men as something that increases risk, and sets healthy weight at a BMI of 18.5 to 24.9. A tape measure is not a diagnosis. It is a reason to ask about the blood test that is.

The Maine and New Hampshire numbers

Regional figures come from two different places, and they deserve careful credit. For Maine, the American Diabetes Association’s 2023 state fact sheet reports 373,000 people, 35.1% of the adult population, with prediabetes. The same sheet puts diagnosed diabetes at approximately 113,136 Mainers, about 10% of adults, with an additional 32,000 who have diabetes and do not know it, and an estimated 8,174 people diagnosed each year. Maine CDC’s own diabetes pages carry no state prevalence numbers at all, so the ADA sheet is the citation here, not the state.

New Hampshire publishes its own. NH DHHS reports 351,000 people in the state, 32.9% of adults, with prediabetes, meaning blood glucose higher than normal but not yet high enough to be diagnosed as diabetes. Roughly 97,000 people, 9% of adults, have diagnosed diabetes, with an additional 29,000 who have it and do not know, and about 7,000 residents diagnosed every year.

NH DHHS also states the trajectory plainly: without weight loss and moderate physical activity, 15 to 30% of people with prediabetes will develop type 2 diabetes within five years. That is the sentence worth sitting with, because it is the only one on any of these pages that describes what happens next.

What none of it shows is that northern New England is sicker than the country. The state numbers come from different sources and different years than the national ones, so stacking them side by side proves nothing. And the behavior data points the other way. In CDC’s 2023 Behavioral Risk Factor Surveillance System, the share of adults reporting no leisure time physical activity was 22.6% in Maine and 21.2% in New Hampshire, both below the national 24.5%. Maine adults met the aerobic guideline of at least 150 minutes a week of moderate intensity activity at a rate of 66.1%, New Hampshire at 63.3%. Obesity ran 32.6% and 32.8%. These are not idle states.

The seasonal part, which is where living here shows up

What northern New England has is not a year round activity problem. It has a winter.

The scale of it is measurable. At Portland, according to the US Naval Observatory, 21 June 2026 runs from a 5:00 a.m. sunrise to an 8:26 p.m. sunset, 15 hours and 26 minutes of daylight. On 21 December, sunrise is 7:11 a.m. and sunset is 4:07 p.m., which is 8 hours and 56 minutes. The difference is 6 hours and 30 minutes, taken away and handed back every year. Anyone who walks after work in July and drives home in the dark in January already knows this in their legs.

Step counts follow the light. In a study of postmenopausal women wearing pedometers, daily steps were highest in the summer months at 7,616 per day, lower in the fall at 6,293, lowest in winter at 5,304, then rebounding in spring to 5,850. That research was not conducted in Maine or New Hampshire and its participants were a specific group, so read the numbers as a shape rather than a local measurement. The shape is a winter trough of roughly 2,300 steps a day.

Blood sugar has a seasonal shape too, at least among people who already have diabetes. An analysis of 285,705 US veterans with diabetes, covering 856,181 A1c tests over two years, found A1c values higher in winter and lower in summer, with a difference of 0.22, and regions with colder winter temperatures showed larger winter to summer contrasts than warmer ones. The proportion of A1c values above 9.0% swung seasonally from 17.3% to 25.3%. That cohort already had diabetes, and the regional finding is about cold generally rather than New England specifically, so it is not a claim about Mainers without the disease. It is a signal that season is not cosmetic.

The mechanism half comes from a much smaller and much more controlled place. Ten healthy young men cut their daily steps from about 10,501 to about 1,344 for two weeks. On a hyperinsulinemic euglycemic clamp, the reference method for this measurement, their glucose infusion rate fell 17%, driven by reduced peripheral insulin sensitivity, alongside a 7% drop in VO2 max and a loss of leg lean mass. A companion trial pinned down the timing: in nine healthy young men doing 14 days of step reduction with 50% overfeeding, insulin sensitivity estimated using the Matsuda index had already decreased at days 3 and 7, before body composition changed.

Three days. That is the real headline buried in this literature, and it is the closest thing to an early signal in the whole subject, except that it is still nothing a person can feel. Nobody in those trials reported a symptom. The change showed up on a clamp and on an index, in young healthy volunteers, before anything visible happened to them at all.

The version worth carrying around

Insulin resistance does not generally announce itself. There is one documented skin sign, and its absence means nothing. There is no routine clinical test for the condition itself, and the diagnosis that does get made, prediabetes, comes from an A1C, a fasting glucose, or a glucose tolerance test at cutpoints NIDDK and the ADA both publish openly. The USPSTF recommends screening a defined group of adults who have no symptoms, which is an admission in guideline form that symptom watching fails here.

The regional angle is not that we are worse off. It is that activity here swings with 6 hours and 30 minutes of daylight, and that controlled research shows peripheral insulin sensitivity responding to a large drop in daily movement inside two weeks. What to do about any of that belongs in a conversation with a clinician who can order the test and read it against your own history.

Food sits alongside all of this rather than inside it. Our guide to anti-inflammatory eating in northern New England covers what a Maine or New Hampshire kitchen has to work with through the cold months, and our look at what NHANES data shows about ultra-processed foods and inflammation applies the same skepticism to a neighboring question.

If you are somewhere between 35 and 70, carrying extra weight, and feeling completely fine, you are the exact person that screening recommendation was written for. Feeling fine is the baseline condition here. It is not the all clear.

Sources

• National Institute of Diabetes and Digestive and Kidney Diseases. Insulin Resistance & Prediabetes. NIH. https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes/prediabetes-insulin-resistance
• American Diabetes Association. Diagnosis. https://diabetes.org/about-diabetes/diagnosis
• Centers for Disease Control and Prevention. Preventing Type 2 Diabetes. https://www.cdc.gov/diabetes/prevention-type-2/index.html
• Centers for Disease Control and Prevention. National Diabetes Statistics Report. https://www.cdc.gov/diabetes/php/data-research/index.html
• US Preventive Services Task Force. Screening for Prediabetes and Type 2 Diabetes (2021 recommendation). https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/screening-for-prediabetes-and-type-2-diabetes
• MedlinePlus Medical Encyclopedia, NIH National Library of Medicine. Acanthosis nigricans. https://medlineplus.gov/ency/article/000852.htm
• American Academy of Dermatology. Acanthosis nigricans: Causes, and Acanthosis nigricans: Signs and symptoms. https://www.aad.org/public/diseases/a-z/acanthosis-nigricans-causes
• National Heart, Lung, and Blood Institute. Assessing Your Weight and Health Risk. NIH. https://www.nhlbi.nih.gov/health/educational/lose_wt/risk.htm
• New Hampshire Department of Health and Human Services. Prediabetes. https://www.dhhs.nh.gov/programs-services/disease-prevention/diabetes/prediabetes
• New Hampshire Department of Health and Human Services. Diabetes. https://www.dhhs.nh.gov/programs-services/disease-prevention/diabetes
• American Diabetes Association. The Burden of Diabetes in Maine (2023 state fact sheet). https://diabetes.org/sites/default/files/2023-09/ADV_2023_State_Fact_sheets_all_rev_Maine.pdf
• Centers for Disease Control and Prevention. Nutrition, Physical Activity, and Obesity, Behavioral Risk Factor Surveillance System, 2023 data. https://data.cdc.gov/d/hn4x-zwk7
• US Naval Observatory, Astronomical Applications Department. Rise, Set, Transit and Twilight data for Portland, Maine. https://aa.usno.navy.mil/data/Dur_OneYear
• Tseng CL, et al. Seasonal patterns in monthly hemoglobin A1c values. American Journal of Epidemiology, 2005. https://pubmed.ncbi.nlm.nih.gov/15746473/
• Newman MA, et al. Monthly variation in physical activity levels in postmenopausal women. Medicine and Science in Sports and Exercise, 2009. https://pubmed.ncbi.nlm.nih.gov/19127194/
• Krogh-Madsen R, et al. A 2-wk reduction of ambulatory activity attenuates peripheral insulin sensitivity. Journal of Applied Physiology, 2010. https://pubmed.ncbi.nlm.nih.gov/20044474/
• Knudsen SH, et al. Changes in insulin sensitivity precede changes in body composition during 14 days of step reduction combined with overfeeding. Journal of Applied Physiology, 2012. https://pubmed.ncbi.nlm.nih.gov/22556394/

This article is for informational purposes only and does not constitute medical advice. Consult a qualified healthcare provider before making any health decisions.