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FDA-approved ED drug can significantly reduce blood sugar levels in type 2 diabetics

[May 9, 2023: Staff Writer, The Brighter Side of News]

Numerous diseases are associated with imbalance or dysfunction in gut microbiome. (CREDIT: Shutterstock)

A pilot study conducted at the University of Gothenburg has yielded remarkable results, suggesting that high-dose tadalafil, a medication commonly used to treat erectile dysfunction (ED), may significantly improve long-term blood sugar levels in patients with type 2 diabetes.

The promising findings warrant further investigation in larger studies over extended periods to confirm the medication's effectiveness.


Tadalafil is part of the PDE5 (phosphodiesterase type 5) inhibitor family, which also includes the well-known drug Viagra. These medications are commonly prescribed to treat impotence or erectile dysfunction.

As with all PDE5 inhibitors, self-medication is strongly discouraged due to potential life-threatening interactions with other drugs. According to Professor Per-Anders Jansson from the Sahlgrenska Academy, University of Gothenburg, these medications should always be prescribed by a healthcare professional.


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Unlike other PDE5 inhibitors, tadalafil is long-acting and can be prescribed as a daily dose, making it an ideal candidate for further study. The pilot study included 18 participants, 12 men and 6 postmenopausal women, who were assigned either a high daily dose (20 mg) of tadalafil or a placebo for six weeks.

Following an eight-week break, participants were given the opposite treatment for another six weeks, effectively acting as their own controls.


The primary goal of the study, conducted in collaboration with Sahlgrenska University Hospital and published in the journal eClinicalMedicine, was to investigate whether tadalafil might enhance patients' insulin sensitivity.

Overview of the study design. After a screening visit, eligible individuals were randomised to either treatment at Visit (V) 2. Treatment period 1 comprises V2, 3 and 4 at 3-weeks interval. Then follows a wash-out period of 8 weeks and a cross-over to treatment period 2 with V5, 6 and 7 during another 6 weeks. (CREDIT: eClinicalMedicine)

While no discernible difference was found in this regard, researchers did observe a significant improvement in metabolic control based on measurements of hemoglobin A1c (HbA1c) in blood samples. On average, HbA1c levels decreased by 2.50 mmol/mol, a notable improvement in long-term sugar levels.


Per-Anders Jansson

Jansson, who led the research, explains that the observed improvement in blood sugar levels is comparable to the results seen with new drug candidates that are now considered the fourth treatment option for type 2 diabetes.

HbA1c levels, which are closely monitored in patients undergoing treatment for type 2 diabetes, can indicate the risk of complications such as microvascular damage to the eyes, kidneys, and nerves.

Tadalafil has shown potential as a supplementary treatment for type 2 diabetes, especially for men who also suffer from ED, a condition that affects more than 70% of men with obesity and type 2 diabetes.

However, larger and longer studies are necessary to verify the findings from the pilot study. The current primary treatment for type 2 diabetes combines lifestyle changes with the drug metformin, with several other new drugs developed in the past 10 to 20 years.


The study also found that tadalafil increased blood flow in skeletal muscle, heart, and adipose tissue, as well as having a favorable effect on liver function, where an established marker of fatty liver decreased during drug treatment compared to the placebo. Additionally, researchers observed an increase in glucose uptake with tadalafil treatment compared to the placebo.

Tadalafil treatment (20 mg orally once daily for 6 weeks) significantly reduces Haemoglobin A1c (HbA1c) compared to placebo treatment. (a) Change in HbA1c over respective treatment period (n = 18, full analysis set (FAS) population). (b) Difference in HbA1c-change between periods, comparing placebo and tadalafil treatment for every individual (n = 18, FAS population). Data are presented as mean (95% confidence interval (CI)). (CREDIT: eClinicalMedicine)

Tadalafil, marketed under the brand name Cialis® by pharmaceutical company Eli Lilly and Co, saw its patent expire in 2017, leading to a significant price drop. The reduced cost may pave the way for broader use of the medication.


The study was co-funded by Eli Lilly and Co, the Swedish Research Council, the Swedish Diabetes Association, and the Novo Nordisk Foundation.

For more science and technology stories check out our New Discoveries section at The Brighter Side of News.


Note: Materials provided above by The Brighter Side of News. Content may be edited for style and length.


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