Nearly 39 million people of all ages in the U.S. have diabetes. However, many people don’t know they have it—and by many? We mean millions. The 2024 National Diabetes Statistics Report noted that 8.7 million adults ages 18 and older met the criteria for diabetes but either didn’t know it or didn’t report it.
“High insulin usually doesn’t cause symptoms you can feel right away, and that’s what makes it tricky,” explains Dr. Raj Dasgupta, MD, the chief medical advisor for Sleepopolis. “When signs do show up, they’re worth paying attention to, as they can be early warnings that your body is struggling with insulin resistance, which is the first step toward prediabetes and Type 2 diabetes.”
Dr. Dasgupta says that detecting clues for diabetes can help you make changes, such as reducing sugar intake, before they snowball. Here, doctors reveal a surprising and overlooked signal that you are eating too much sugar and what to do next to protect your health.
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The Overlooked Skin Change That’s a Sign of High Blood Sugar
Darkened patches on the skin—also known as acanthosis nigricans—are a sign you may have high blood glucose, which may be a result of eating too much sugar.
“Acanthosis nigricans can be genetic, but it can also be associated with insulin resistance, obesity, prediabetes or diabetes and polycystic ovary syndrome (PCOS),” reveals Dr. Beth Oller, MD, a family physician.
In rare cases, acanthosis nigricans can be a sign of cancer, explains Dr. Haymar Hann, MD, a board-certified internal medicine physician with Medical Offices of Manhattan and a contributor to LabFinder.com. Yet, often, it’s a sign of high blood sugar, so it’s vital to be on the lookout. She adds that these patches can show up anywhere on the body, but hte most common spots are:
- The nape of the neck
- Armpits
- Groin area
- Under the breasts
“These areas are more prone to friction, which can worsen thickening and darkening of the skin,” explains Dr. Samantha Brand, DipABOM, an obesity medicine physician at Revolution Medicine, Health & Fitness.
Related: This Weird Change Is an Unexpected Sign of Diabetes That Doctors Are Begging People To Pay Attention To
What Causes Acanthosis Nigricans?
High blood glucose can cause darkened patches to appear on the neck, armpits and other body parts. Dr. Brand says insulin resistance is the most common cause for these patches, which are clinically known as acanthosis nigricans. Eating a ton of sugar can contribute to insulin resistance.
“Eating too much sugar raises blood sugar levels, prompting an increase in insulin to bring those levels down,” she says. “Insulin also activates certain skin cells that have insulin receptors.”
Specifically, Dr. Brand explains that insulin can trigger:
- Melanocytes, which produce melanin (the pigment that gives skin its color)
- Keratinocytes, which make keratin (a protein that helps form the outer layer of the skin)
“When insulin levels are persistently high—in those with insulin resistance or prediabetes—it can overstimulate both melanocytes and keratinocytes, leading to increased production of melanin and keratin,” she continues. “This results in thick, dark, velvety patches of skin, called acanthosis nigricans.”
Related: The Silent Symptom of High Blood Sugar You Should Never Ignore, According to Endocrinologists
What To Do if You Notice Dark Patches on the Skin
It’s important to speak with your doctor if you think you have acanthosis nigricans, whether or not you suspect you have prediabetes or Type 2 diabetes.
“The spots themselves aren’t harmful, but determining the cause of acanthosis nigricans is crucial because it is often a sign of an underlying condition, such as insulin resistance, hormonal imbalances, or, in some cases, cancer,” Dr. Dasgupta says.
He explains that a diagnosis of the condition itself often doesn’t take much time, sharing, “Doctors usually diagnose acanthosis nigricans just by looking at it—the appearance is very distinctive.”
Dr. Oller says they may order bloodwork or—rarely—a skin biopsy to be sure.
Related: The Simple Post-Dinner Habit That Slashes Your Diabetes Risk
Will Acanthosis Nigricans Go Away on Its Own?
It likely won’t, and doctors don’t advise waiting for it to clear up. “Acanthosis nigricans can improve or resolve if the underlying cause is treated, although this process may be slow, several months to years,” Dr. Brand explains. “In some cases, it may persist despite addressing the cause. Consulting a dermatologist can help speed up the process with targeted skin treatments.”
Dr. Hann shares that a dermatologist may recommend:
- Prescription cream to lighten the area
- Laser therapy or dermabrasion to reduce thickness
- Vitamin A to help clear the skin
Related: This Is the #1 Best Habit for Blood Sugar Balance, According to an Endocrinologist
Tips for Lowering Blood Sugar
Dr. Brand shares that the best way to treat acanthosis nigricans is to address the root cause, which is usually high blood sugar. A doctor can work with you on lifestyle tweaks and potentially medications to keep you healthy. They may recommend:
- A low glycemic diet that limits processed and refined carbs (like white bread) and prioritizes whole grains, legumes and high-fiber starches
- Regular physical activity, including resistance training to increase muscle mass and aerobic exercise (think walking, biking or swimming)
- Medications, such as Metformin or GLP-1 receptor agonists
Of course, you need to know you have high blood sugar to get the support you need. That’s why she says it’s vital to take note of signs of insulin resistance and call your doctor.
“Being aware of any changes or new symptoms allows you to take action sooner, improving management and preventing severe complications,” she emphasizes.
Up Next:
Related: The One Thing You Should Never, Ever Do if You Want To Avoid Getting Diabetes
Sources:
- National Diabetes Statistics Report. CDC.
- Dr. Raj Dasgupta, MD, the chief medical advisor for Sleepopolis
- Dr. Beth Oller, MD, a family physician
- Acanthosis nigricans and the metabolic syndrome. Clinics in Dermatology.
- Dr. Haymar Hann, MD, a board-certified internal medicine physician with Medical Offices of Manhattan and a contributor to LabFinder.com
- Dr. Samantha Brand, DipABOM, an obesity medicine physician at Revolution Medicine, Health & Fitness
