RELATED: If You Notice This in the Bathroom, Get Checked for Diabetes, Experts Say. Those with diabetes may experience a range of skin changes related to the disease. In particular, many people with diabetes develop a condition known as acanthosis nigricans, which appears in the form of “dark, thickened, velvety skin” surrounding skin creases. Though acanthosis nigricans can also appear around the groin, neck, elbows, knees, or chest (underneath the breasts), many people develop this darkened skin inside their armpits. “The affected skin may also have an odor or itch,” explains the Mayo Clinic. Some people may also notice skin tags—or small, soft growths—in the affected area. RELATED: If You Notice This on Your Legs, Get Checked for Diabetes Now, Experts Say. Though you’re more likely to develop this particular skin condition as a result of advanced disease, the American Academy of Dermatology Association (AADA) notes that it can also “be the first sign that someone has diabetes.” In fact, in some cases it can appear in the prediabetic stage, while the disease is still considered reversible. That’s why, if you do notice this type of skin discoloration, it’s important to follow up with your doctor immediately. There may still be time to prevent diabetes through lifestyle changes such as an improved diet, exercise, quitting smoking, and blood sugar management. For more health news sent directly to your inbox, sign up for our daily newsletter. Diabetes can change your skin in many ways: you may develop blisters, shin spots, digital sclerosis, or foot ulcers, to name just a few. However, if you’ve developed acanthosis nigricans, it may be because having too much insulin in the body can cause skin cells to reproduce rapidly, experts say. “For people with skin that has more pigment, these new cells have more melanin,” explains Healthline. “This increase in melanin produces a patch of skin that’s darker than the skin surrounding it.“ae0fcc31ae342fd3a1346ebb1f342fcb Because the pigmentation of your skin can make you more or less likely to develop this condition, individuals from certain ethnic backgrounds are considered at greatest risk. The AADA points out that people with African, Caribbean, South or Central American, or Native American ancestry are most likely to experience acanthosis nigricans. A case of acanthosis nigricans most often indicates insulin resistance, but it can have other underlying causes. When not associated with diabetes or prediabetes, your darkening, thickening skin may be caused by obesity or a glandular disorder, according to the AADA. Less often, it’s linked to Addison’s disease, a pituitary disorder, growth hormone therapy, or thyroid problems. It’s also considered a potential side effect of certain medications, including oral contraceptives. In rare cases, acanthosis nigricans may indicate a cancerous tumor in an internal organ like the stomach or liver. It’s important to note that acanthosis nigricans can occur in otherwise healthy individuals, so the dark band of skin in your armpits may be perfectly harmless. Speaking with your doctor can help determine whether your particular skin changes are cause for concern. RELATED: If You See This on Your Nails, It Could Be a Tell-Tale Sign of Diabetes.