Diabetes is a disease rising in prevalence. About 1 in 3 Americans are at risk for developing type 2 diabetes, and many don’t even know it.
The chances of knowing somebody with diabetes are likely very high; it could even run in your family.
Prediabetes is a condition where blood sugars are higher than usual but not high enough to be considered diabetes. Having prediabetes is a significant risk factor for developing diabetes later on. One of the causes of both prediabetes and diabetes is insulin resistance.
Insulin resistance and blood sugar problems often have no apparent symptoms until it’s progressed into diabetes. However, acanthosis nigricans is one visible sign of insulin resistance.
Knowing what acanthosis nigricans is, how it’s related to diabetes risk, and what other things it can mean can help people make early interventions if they suspect a problem with their health.
What is acanthosis nigricans?
Acanthosis nigricans is a skin condition characterized by dark, velvety patches of skin. These patches typically appear in skin folds, such as on the neck, groin, and armpits. The borders of the dark patches are usually not well-defined unless the patches of discolored skin become thickened.
Acanthosis nigricans typically affects people who are overweight and who have blood sugar problems. However, it can also occur in people without diabetes, but it’s much less common. Children can also develop acanthosis nigricans.
While acanthosis nigricans doesn’t typically cause pain, some people may notice their skin becoming itchy or having a foul odor as it progresses.
People affected by acanthosis nigricans may also have skin tags since skin tags and insulin resistance are often associated together. As the skin thickens from acanthosis nigricans, the borders of the affected skin may become more apparent.
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Who is at risk for acanthosis nigricans?
People who are at risk for developing diabetes are typically the most at risk of developing acanthosis nigricans.
Children who develop acanthosis nigricans are more likely to have type 2 diabetes later in their life. This condition often develops during childhood and puberty but can affect people of all ages.
Risk factors for developing type 2 diabetes and acanthosis nigricans include:
- Weight: people who are considered overweight or obese according to their body mass index (BMI).
- Age: people 45 and older are at increased risk.
- Family history of diabetes
- Race/ethnicity: diabetes tends to affect individual races more than others. At-risk races include African American, Alaska Native, Native American, Asian American, Hispanic/Latino, Native Hawaiian, or Pacific Islander.
- High blood pressure: if your blood pressure is higher than 120/80, you may be at increased risk.
- Altered lipid levels: low levels of HDL “good” cholesterol and high levels of LDL “bad” cholesterol are risk factors, as well as high triglycerides (blood fat).
- Pregnancy history: women with a history of gestational diabetes (GDM) or gave birth to a baby 9 pounds or heavier are at increased risk.
- Physical activity: people who aren’t regularly active or have a sedentary lifestyle are at increased risk.
- Smoking status: Smokers are 30-40% more likely to develop type 2 diabetes than nonsmokers.
- Health history: those with a history of heart attack or stroke have a higher likelihood of developing type 2 diabetes.
- PCOS: Polycystic Ovarian Syndrome in women is a risk factor, as it usually is associated with insulin resistance.
What causes acanthosis nigricans
Acanthosis nigricans is typically caused by insulin resistance. Insulin is a hormone produced by the pancreas and is responsible for allowing sugar (glucose) into our cells.
Cells have insulin receptors, which insulin attaches to in order to let the sugar in. An easier way to think of it is that the cells have doors, the insulin receptors are the doorknobs, and insulin is the key to open the doorknob.
Insulin resistance occurs when there is either insufficient insulin (keys) produced by the pancreas, or the body doesn’t respond to insulin-like it should (keys aren’t working to open the doors).
Without enough insulin, blood sugar is left to accumulate in the bloodstream instead of feeding our cells, causing high blood sugar and diabetes.
Acanthosis nigricans is also associated with other health conditions, such as:
- Hormonal disorders like thyroid problems, adrenal imbalances, and ovarian cysts.
- Certain drugs and supplements such as high-dose niacin (vitamin B3), birth control pills, and corticosteroids such as prednisone.
- Cancer is a rarer cause of acanthosis nigricans but has been associated with lymphoma as well as cancers of internal organs. When acanthosis nigricans is associated with cancer, it’s called malignant acanthosis nigricans (AN) and is often derived from glandular tissue (adenocarcinoma), particularly of the stomach (gastric adenocarcinoma). Malignant acanthosis nigricans typically affects people age 40 and older.
Diagnosis
According to the National Organization For Rare Disorders, acanthosis nigricans “may be diagnosed based upon thorough clinical evaluation, identification of characteristic physical findings, a complete patient history (including careful medication history), a thorough family history, and various specialized tests.”
Symptoms of acanthosis nigricans may be similar to other conditions, so a differential diagnosis needs to be made to rule out conditions such as:
- Addison’s disease – an endocrine disorder.
- Becker nevus – a late-onset birthmark in males.
- Gougerot-Carteaud syndrome – a rare skin disorder that more commonly affects women and girls.
- Ichthyosis hystrix – a rare genetic skin disorder.
- Parapsoriasis en plaque – an uncommon condition resulting in scaly skin plaques.
When acanthosis nigricans isn’t caused by cancer (such as from insulin resistance, genetics, or medication-caused), it’s called benign acanthosis nigricans.
Treatment
Treatment of acanthosis nigricans depends on its primary cause. For most people, the cause is insulin resistance and blood sugar imbalances, such as type 2 diabetes. Therefore, a common treatment is to improve blood sugar levels. This can be done through a combination of lifestyle modifications as well as medication use.
There are many medications available for the treatment of diabetes. Insulin is typically the only medication used for type 1 diabetes and is often used to treat type 2 diabetes as well. Insulin comes in several forms, including long-lasting/basal, intermediate-acting, and short-acting/mealtime.
There are several other treatment options available for use in type 2 diabetes. Some of the more popular medications include:
- Metformin: Helps to reduce the amount of sugar released by the liver and improves insulin sensitivity
- Sulfonylureas: Stimulate the pancreas to secrete more insulin
- GLP1 receptor agonists: Promote insulin production, decrease glucose release from the liver and slows stomach emptying to increase satiety
- DPP-4 inhibitors: Promote insulin production, decrease glucagon (a hormone that increases blood sugar) production, and delays gastric emptying.
Lifestyle changes can also be made to improve insulin resistance and acanthosis nigricans. Some of the best habits to implement to improve blood sugars include:
- Being physically active for at least 30 minutes most days of the week. A combination of cardiovascular exercise (such as walking) and strength training is ideal.
- Eating a healthy diet. Diets rich in whole grains, fruits, vegetables, legumes and nuts, moderate in alcohol, and low in refined (white) grains, red meat and sugar-sweetened beverages have been found to promote healthy blood sugar levels. A Mediterranean diet is linked with a lower incidence of disease and mortality and has been shown to reduce diabetes risk in those at high risk of cardiovascular disease.
Prevention
Acanthosis nigricans is most commonly associated with insulin resistance and diabetes. Therefore, ways to prevent acanthosis nigricans are the same things that can help prevent blood sugar imbalances and diabetes.
While type 2 diabetes and prediabetes tend to run in families, some lifestyle habits can help reduce your risk of getting diabetes. Some things you can do to prevent insulin resistance and acanthosis nigricans include:
- Have blood sugar levels screened based on your risk factors: people should start to receive blood sugar screenings at age 45, and sooner for those with other risk factors for developing diabetes.
- Cut back on sugar. While eating sugar doesn’t cause diabetes, a higher intake of sugar has been associated with an increased risk of diabetes, along with many other factors. Added sugars tend to be especially detrimental to health since they don’t provide any nutritional value and cause large blood sugar fluctuations.
Added sugar is hidden in many common foods, making it hard to avoid for those who don’t know how to identify added sugar. Foods that are marketed as healthy can be very high in sugar, such as yogurts, cereal, and nutrition bars. Added sugar is also hidden in less-obvious foods like pasta sauce, salad dressings, and condiments.
The American Heart Association recommends that women consume no more than 6 teaspoons of added sugar per day (24 grams) and men consume no more than 9 teaspoons of added sugar per day (36 grams).
- Exercise. Being physically active is a very important way to reduce the risk of type 2 diabetes. 150 minutes per week of moderate physical activity, such as brisk walking, is associated with a reduction in diabetes risk. Promoting muscle mass through resistance training is also associated with improved blood sugar and reduced insulin resistance. Having an exercise routine with both cardiovascular and strength training exercises is ideal.
- Quit smoking. Smokers are 30-40% more likely to develop type 2 diabetes than nonsmokers. Smoking also increases the risk of cardiovascular disease, which can lead to heart attack and stroke. Having type 2 diabetes increases the risk of heart disease, as well. (For more information on smoking in regards to diabetes risk, as well as tips for quitting, check out our post here.)
There are several other helpful things you can do to reduce your diabetes risk; read about them here.
Conclusion
Acanthosis nigricans is a skin condition resulting in dark, velvety patches of skin. The affected areas tend to be in skin folds, such as the neck, armpits, and groin. They usually aren’t painful but may be itchy and become thickened over time.
The most common cause of acanthosis nigricans is from insulin resistance, which is the main cause of type 2 diabetes. This type is called benign acanthosis nigricans because it’s not a sign of cancer. People may develop acanthosis nigricans when they have prediabetes, and it hasn’t fully progressed to type 2 diabetes.
Making lifestyle changes can help reverse prediabetes and prevent type 2 diabetes, so it’s important to keep up with regular preventive healthcare screenings and visits.
More rarely, acanthosis nigricans can be a sign of cancer. This is called malignant acanthosis nigricans, and typically affects people older than 40 years, whereas benign acanthosis nigricans can affect people of all ages, including children.
Acanthosis nigricans can be diagnosed during a visit with your healthcare provider using a physical exam, patient history, and blood tests. If acanthosis nigricans is caused by insulin resistance, it can be treated with healthy lifestyle changes and/or medications to help improve blood sugar levels.
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