Are men taking 5α-reductase inhibitors for an enlarged prostate more likely to develop type 2 diabetes?

This study examined if men taking 5α-reductase inhibitors (5ARIs) for benign prostatic hyperplasia (BPH) are more likely to develop type 2 diabetes (T2D). This study concluded the risk of developing T2D is higher in patients taking 5ARIs for BPH, compared to alpha blockers. 

Benign Prostatic Hyperplasia (BPH) is a non-cancerous enlargement of the prostate gland. An enlarged prostate can affect bladder function and have a negative impact on quality of life. Treatments for BPH may include medication or surgery. Medications for BPH often result in many side effects. Surgery can also lead to complications. 

5ARIs such as finasteride (Proscar) and dutasteride (Avodart) may stop prostate growth. They do this by stopping male sex hormones being made. Tamsulosin (Flomax) is an alpha-blocker. This means that it relaxes the muscles in the bladder neck. The relaxation of these muscles allows for easier urine flow out of the body.

Many types of drugs are involved in increasing the risk of T2D. It is not known if 5ARIs increase the risk of developing T2D in patients with BPH. 

This study looked at the medical records of 146983 men in the UK and Taiwan. All patients included in these studies received either dutasteride, finasteride, or tamsulosin. Patients were followed up for an average of 5.2 years for new onset of T2D. 

In the UK group, there were 2081 new cases of type 2 diabetes. Patients taking dutasteride were 1.32 times more likely to develop T2D when compared to those taking tamsulosin. Patients taking finasteride were 1.26 times more likely to develop T2D, compared to those taking tamsulosin.
 
In the group of Taiwanese patients, those taking dutasteride were 1.34 times more likely to develop T2D, when compared to those taking tamsulosin. Patients taking finasteride were 1.49 times more likely to develop T2D, compared to those taking tamsulosin.

The risk of developing T2D was similar for those taking dutasteride and finasteride. 

This study concluded that the risk of developing type 2 diabetes is higher among patients taking 5ARIs for BPH compared to alpha-blockers. 

This study looked at the medical records of patients. Some patients received only a short course of these medications. Further studies are required. 

If you have concerns regarding BPH medications, please consult with your doctor.