Sildenafil and Diabetes

Can Viagra Cure Diabetes?

Every other week there is a new treatment for something new. I was delighted today to be alerted to a new cure for diabetes: Sildenafil. Sildenafil commonly trades under the name of Viagra. So yes, Viagra is the new cure for diabetes according to many news sources. As any rational person would, I get skeptical when the word ‘cure’ pops up around incurable diseases. Sildenafil works by inhibiting phosphodiesterase 5 (PDE5) found in various tissues within the body. This causes a relaxation in smooth muscle, increased blood flow and vasodilation. As you may know, Viagra is a common treatment for erectile dysfunction and less commonly known for its treatment of pulmonary arterial hypertension (high blood pressure). There are a lot of problems with sildenafil as a medicine and an even greater amount of problems with counterfeiting. The media has caught onto a study that indicates Viagra can increase the secretion of insulin and ‘prevent’ the onset of type two diabetes.

The Study

The study in question was published in the The Journal of Clinical Endocrinology & Metabolism university entitled: Treatment with Sildenafil Improves Insulin Sensitivity in Prediabetes: A Randomized, Controlled Trial. The study separated 42 people into two groups, one of which was orally dosed with 25mg of Viagra 3 times a day whilst the other group received placebo. Three months later, insulin sensitivity was significantly greater in the sildenafil group compared to the placebo. I have a few gripes with this study, we’ll take them one by one:


Firstly; the subjects. All subjects were overweight people with ‘prediabetes’. This is essentially a stage where not all symptoms of diabetes are present, but there is a disposition. So we have study using drugs to cure diabetes in patients who do not technically have diabetes. That’s the equivalent of saying eating grass cures cancer in people that don’t have cancer. Insulin secretion isn’t uniform within the subjects, hardly makes this fair game. We have 31 subjects taking other medicines throughout the study. In their chart of all the data, they include data for 9 people that were excluded from the study, which leads to highly inaccurate results. The table of information states that only 15 of the subjects (n=25 as we appear to be including those who were dismissed) had impaired glucose levels. I was under the impression they all had impaired glucose levels as they're pre-diabetic, or is that not a requirement of pre-diabetes?

Secondly; the sample size of the study. The study uses statistics to reinforce the result with a p-value of .049, which is excellent. Wait, in 42 patients? The number of samples in each group really affects reliability of these trials. That’s 21 patients in each group. 21 people without diabetes, but showing some high levels of blood sugar took sildenafil and had an increased insulin secretion. So, do we have a cure? Not necessarily, small sample sizes create very big holes in these studies. With over 400 people being diagnosed with diabetes in the UK alone each day, surely that sample size could be larger? It’s surely not hard to find somebody with pre-diabetes, 42 subjects don’t really cut it enough to make such a large conclusion. In America, where the study was produced, diabetics are on the rise, it is a huge problem over there, but they could only use 42 patients?

Thirdly; their conclusion. They conclude with saying that this is somewhat preliminary and semi-speculative along with the fact that this could possibly be used to prevent formation in ‘high risk’ patients. My problem here is that they don’t state there is a cure, so why does the media portray it so? Even more, they state that further research is required, which is about as scientifically useful as saying 'water is wet'. More research could always be carried out to reinforce a point, always.

Fourthly; the medical implications. No medicine is without risks, which doesn’t appear to have been assessed in the study. Metabolic problems of sildenafil include: unstable blood sugar and hyperglycemia. Obviously both common problems in diabetic patients. Lest we forget the common side effects of respiratory, dermatological and hematological problems involved with the absorption of Viagra.

 

Media

Obviously the media hasn’t looked at the study in the same way you would as if you were going to report on something. You read it. Many of the major news outlets such as SKY or BBC have not (as of yet) picked up on this news break. But many other news sources have. Using ‘Viagra can cure diabetes’ as the headline. The Mirror used this headline, up until around 7pm when it was changed to ‘could stop you getting type 2 diabetes’ – which is a little more accurate in context of the study, but not accurate in terms of a wider picture. I am somewhat relieved to see that this article and the express are the only ones to really pick up on this and run with it, although I have no doubt that others will emerge. The express has a little differentiation in the story to The Mirror using a larger subject sample size n=51. I have read this study twice already and this goes to show how well they actually read the study. 51 people started, with 9 being dismissed from the study, leaving a total of 42 subjects. They also state:

Doctor Nancy Brown, of Vanderbilt University School of Medicine in the US, said: "Weight loss and exercise regimens can be difficult to maintain, and some current medications have been limited by concerns about adverse effects."

Really? Concerns about adverse effects in comparison to sildenafil? In 2007, the FDA stated that all PDE5 inhibitors required extra labelling for the adverse effects and potential sudden loss of hearing.
A drug that has a high number of related cardiovascular problems and deaths is more beneficial than something like metformin with mild side effects?

Conclusion

I recently wrote about diabetes ‘cures’ and how the media utilized bad science to propagate pseudoscientific nonsense. When I read this article on my lunch break it said nothing of the type of diabetes; type one or two. It also only really used conclusive terminology; ‘will cure’. Let’s be clear here, if this preliminary study is repeated on a larger scale double blind clinical trial and found to have more conclusive results, then we haven’t found a cure. We are looking at people who have a disposition to type two diabetes, these are at a point in which they don’t have diabetes and can revert via a change in lifestyle. So, if a change in lifestyle can reverse the effects of type two diabetes, which it can (in the early stages) then why would you take medicine with a higher risk of side effects? There is no cure being discovered here, in the same way that injectable insulin isn't a cure in type one diabetes. The problems with articles like this is that they cause more harm than good. People can read the version of the article I read and fully (albeit, naively) believe it. Taking the drug when you have no medical need for such a thing is blindly stupid. Precaution should be taken and these studies read carefully, unfortunately peer review and publishing scientific papers isn't a smooth and flawless process, cracks form and some fall through that are below standard.

Although, it would be interesting to see the results of a larger scale study (and a better subject sampling), things like this are not funded due to the holes that already really exist. This study has many issues with the subjects and the criteria for statistical analysis. Many preliminary studies like this tend to just stay as is; preliminary.