Curative Cushing Syndrome Procedure Improves or Resolves Hyperglycemia

Credit: Unsplash / Matt C

An analysis of data over 20 years from the Mayo Clinic showed that being cured of Cushing syndrome resulted in most patients resolving or improving their hyperglycemia over time.

The real-world study of 174 adult patients with the condition is, according to the investigators, the first to assess long-term changes in patients to receive a curative procedure "based on the time from the curative surgery, to assess the changes in the intensity of hyperglycemia therapy and identify predictors for hyperglycemia improvement."

A team led by Irina Bancos, MD, endocrinologist at the Mayo Clinic Rochester, designed the study with an interest in examining the impact of curative procedures on hyperglycemia and its management in patients with Cushing syndrome from electronic medical record data of patients treated at a referral center from 2000 to 2019. The primary purpose of the study was to assess the impact of curative procedures on extent of hyperglycemia and the secondary aim was to investigators how baseline factors might influence improvement of hyperglycemia at follow-up.

For inclusion in the analysis, patients needed to be at least 18 years of age, diagnosed with Cushing syndrome, and have hyperglycemia treated with a curative procedure from 2000 to 2019.

For the purpose of analysis, Cushing syndrome was diagnosed based on clinical evaluation by an endocrinologist and diagnosed according to the most recent guidelines. Hyperglycemia was defined according to American Diabetes Association guidelines.

The primary outcome of interest for the study was the resolution of hyperglycemia following resolution of Cushing syndrome. For the purpose of analysis, resolution was defined as absence of hyperglycemia without the need for antihyperglycemic therapy. Secondary outcomes of interest included changes in HbA1c, and the intensity of hyperglycemia management.

Overall, 174 patients were identified for inclusion in the study. This cohort had a median age of diagnosis of 51 years and 73 percent were women. When assessing subtype of Cushing syndrome, the most common form was pituitary Cushing syndrome, followed by ectopic and adrenal. The median baseline HbA1c was 6.9 percent. Additionally, 24 percent of patients were not on any therapy for hyperglycemia, 52 percent were on oral medications, and 37 percent were on insulin.

When assessing differences between subtypes, results indicated those with pituitary Cushing syndrome were younger at the time of surgery, and included more women, and reported a longer duration of symptoms prior to diagnosis. Investigators noted patients with pituitary Cushing syndrome also had the highest clinical severity score, but patients with ectopic Cushing syndrome had the highest biochemical severity score.

Following Cushing syndrome remission and at the end of follow-up, which occurred at a median of 10.5 months, 21 percent of patients demonstrated resolution of hyperglycemia, 47 percent demonstrated improvement, and 32 percent had no change or worsening hyperglycemia. When assessing secondary end points, results indicate HbA1c decreased by 0.84 percent and daily insulin dose decreased by a mean of 30 units.

Further analysis indicated hypercortisolism severity score and Cushing syndrome subtype were associated with hyperglycemia improvement, but not type of hyperglycemia at the end of follow-up.

“We demonstrated that almost 70 percent of patients with (Cushing syndrome) demonstrate either resolution or improvement in hyperglycemia following remission," investigators wrote. "As a group, patients demonstrate a decrease in HbA1c, and can be treated with less insulin and fewer non-insulin agents. Patients with more severe hyperglycemia, ACTH-dependent Cushing syndrome, and more severe Cushing syndrome are more likely to improve after surgery."

An original version of this article was published on sister site HCPLive.