Cushing’s disease is rare. Roughly 1.2 to 2.4 new cases are diagnosed per million people each year, making it one of the least common hormonal disorders. To put that in perspective, in a city of one million people, only one or two residents would receive a new diagnosis in a given year. The total number of people currently living with Cushing’s syndrome from all causes is estimated at 57 to 79 per million.
Cushing’s Disease vs. Cushing’s Syndrome
The two terms are related but not interchangeable. Cushing’s syndrome is the umbrella term for any condition that causes the body to produce or receive too much cortisol, the hormone that regulates stress response, metabolism, and inflammation. Cushing’s disease is one specific cause: a small, usually noncancerous tumor on the pituitary gland that drives cortisol overproduction. It accounts for 60 to 80% of all cases of endogenous Cushing’s syndrome, making it far and away the most common internal cause.
The remaining cases come from tumors on the adrenal glands or, less often, from tumors elsewhere in the body that produce the same signaling hormone the pituitary does. There is also a large population of people with Cushing’s syndrome caused by long-term use of corticosteroid medications, but those cases are categorized separately because the excess cortisol comes from an outside source.
Who Gets Cushing’s Disease
Women are about three times more likely to be diagnosed than men. The condition is most commonly identified in adults between their 20s and 50s, though it can appear at any age. A nationwide Swedish study tracking cases over 26 years found a steady incidence of about 1.6 cases per million annually, with a slight uptick in the most recent decade to 2.0 per million. A U.S. study reported higher numbers, between 6.2 and 7.6 per million, which may reflect greater screening or differences in how cases were counted.
In children, Cushing’s disease is even rarer. Only about 10% of all new Cushing’s syndrome cases each year occur in people under 18. Among children older than 7, the pituitary form (Cushing’s disease) still accounts for roughly 75% of cases. In children younger than 7, adrenal tumors are more common. The average age of diagnosis in pediatric cases is between 10 and 14 years, and unlike in adults, the gender split in children is closer to even.
Hidden Cases in High-Risk Groups
The official incidence numbers likely undercount the real burden. A 2024 study published in Diabetes Care screened over 1,000 people with difficult-to-control type 2 diabetes and found that nearly 24% had lab results suggesting excess cortisol production. Among those also taking three or more blood pressure medications, the rate climbed to almost 37%. Most of these people had never been evaluated for a cortisol disorder.
This doesn’t mean a quarter of people with stubborn diabetes have full-blown Cushing’s disease. Many of these cases are what clinicians call subclinical, meaning cortisol levels are elevated enough to show up on a test but haven’t yet produced the classic physical signs like a rounded face, central weight gain, or purple stretch marks. Still, even mild chronic cortisol excess worsens blood sugar, raises blood pressure, and weakens bones, so these hidden cases carry real health consequences.
Why Diagnosis Takes So Long
One of the most frustrating aspects of Cushing’s disease is how long it takes to identify. A meta-analysis of over 5,300 patients found the average time from first symptoms to confirmed diagnosis was 38 months for the pituitary form, just over three years. That’s longer than adrenal Cushing’s (30 months) and significantly longer than cases caused by ectopic tumors (14 months).
The delay happens because early symptoms overlap with extremely common conditions. Weight gain, fatigue, mood changes, high blood sugar, and high blood pressure are everyday complaints in a primary care office, and most of the time they have nothing to do with cortisol. Cushing’s disease doesn’t usually announce itself with one dramatic symptom. Instead, it layers problems gradually: thinning skin that bruises easily, muscle weakness in the thighs and upper arms, a fatty pad developing between the shoulders, irregular periods, and facial rounding. By the time someone has several of these features together, years may have passed.
Treatment Outcomes and Recurrence
The primary treatment is surgery to remove the pituitary tumor through the nose and sinuses, a procedure called transsphenoidal surgery. In a large case series of over 1,100 patients tracked across 30 years, the initial remission rate was 72.5%. Outcomes were better for smaller tumors: patients with microadenomas (tumors under 10 mm) achieved remission about 74% of the time, compared to 66% for larger tumors. Patients whose tumor hadn’t invaded surrounding tissue did better still, with remission rates around 77%.
Even after successful surgery, recurrence is a real concern. A recent 10-year follow-up study found that among patients who initially went into remission, 27.4% eventually relapsed, with recurrences detected at a median of about three years after surgery. Patients with larger tumors had a much higher recurrence rate, 45% compared to 19% for those with smaller tumors or no visible lesion on imaging. This is why long-term monitoring with regular cortisol checks continues for years after surgery.
For patients who don’t achieve remission with surgery or who relapse, options include repeat surgery, radiation therapy targeting the pituitary, medications that lower cortisol production, or in some cases removal of both adrenal glands. Each approach has tradeoffs, and the path forward depends on the size of the remaining tumor and how much cortisol it’s producing.
Rarity Doesn’t Mean Insignificant
Cushing’s disease sits firmly in the category of rare diseases, but its health impact is disproportionate to its numbers. Untreated, it significantly raises the risk of heart disease, stroke, blood clots, infections, and bone fractures. Even after successful treatment, some patients deal with lingering effects on metabolism, bone density, and mental health for years. The combination of delayed diagnosis and meaningful recurrence rates means many patients spend a decade or more actively managing the condition and its consequences.