Many type 2 diabetes patients have trouble finding an effective glucose-controlling prescription medication that doesn’t include serious side effect risks. When someone reacts badly to certain blood sugar drugs, respiratory infections, diabetic amputation or coma, and even death may occur. Recently, two large clinical trials concluded Janssen Pharmaceuticals’ popular diabetes medication, Invokana, more than doubles diabetic amputation rates in patients. For this reason, the U.S. Food and Drug Administration recently warned consumers that Invokana (canagliflozin) significantly raises diabetic amputation risks. If you or someone you love currently takes Invokana, Invokamet or Invokamet XR, learn more about clinical trial data below.
FDA Confirms Increased Toe, Leg and Foot Diabetic Amputation Risks
In May 2017, the FDA released a black box warning regarding increased diabetic amputation risks for toes, legs and feet. The FDA’s black box warning is reserved for dangerous drugs and medical devices that warrant heightened safety communications for consumers. This warning requires Janssen (a Johnson & Johnson subsidiary company) to add prominent new labels on all Invokana drug packaging.
The FDA’s warning came as a result of two randomized, double-blind clinical trials on type 2 diabetics taking Invokana.
Study #1: CANVAS Clinical Trial Results
First, let’s take a closer look at the CANVAS (Canagliflozin Cardiovascular Assessment Study) finalized trial results. Researchers discovered twice as many leg and foot amputations in patients treated with Invokana compared to those given a placebo. The most common diabetic amputation forms recorded among 4,330 study participants were the toe and middle of the foot. Yet other diabetic amputation cases reported among the study’s findings included patients’ legs, both below and above the knee. Some subjects required diabetic amputation of both limbs or needed multiple amputations over the nearly six-year study period.
The CANVAS results showed that during a one-year timeframe, 5.9 in 1,000 subjects taking Invokana required a lower-limb diabetic amputation. By comparison, 2.8 in 1,000 study participants given the placebo needed a diabetic amputation during that same 12-month period. These findings were unexpected, since researchers were primarily comparing cardiovascular outcomes in type 2 diabetes patients taking Invokana vs. placebo.
Study #2: CANVAS-R Clinical Trial Results
The second clinical trial involving type 2 diabetes patients taking Invokana, Invokamet or Invokamet XR showed even more frightening results. This second trial is titled CANVAS-R (Effects of Canagliflozin on Renal Endpoints in Adult Participants With Type 2 Diabetes Mellitus). The CANVAS-R researchers measured renal outcomes for 5,812 subjects taking Invokana (i.e., kidney damage or failure) compared to a placebo. The CANVAS-R trials found that 7.5 in 1,000 study subjects treated with Invokana required a diabetic amputation within one year. Compare that to 4.2 in 1,000 study participants who needed a diabetic amputation while taking the placebo during that timeframe.
The most frequent amputations reported by clinical trial participants included lower limbs or toes. The FDA reports that most diabetic amputation procedures were due to lower-limb infections, gangrene, diabetic foot ulcers, and ischemia. While diabetic amputation risks are well-known (one study states they’re eight times higher than for non-diabetics), Invokana increases that danger.
Why Would Type 2 Diabetics Need Lower-Limb Amputations?
Type 2 diabetics with poorly regulated blood sugar may develop peripheral arterial disease or PAD. A PAD diagnosis means fatty deposits block or narrow your blood vessels, thereby reducing blood flow to legs and feet. It can also cause nerve damage, which prevents you from feeling pain in your lower extremities. This nerve damage (also known as peripheral neuropathy) could then keep you from noticing a wound or ulcer on your feet. Putting continued pressure on an affected area can cause or help spread further infection.
Reduced circulation also inhibits healing, making it much harder to fight off those infections with poor blood flow. Eventually, the infected wound can result in tissue damage or gangrene, spreading infection to your bones and throughout your body. When an infection like that goes too far, diabetic amputation may be your only option. Because PAD symptoms typically affect your toes, feet and lower legs, they’re the most likely areas to require diabetic amputation.
In 2010, 73,000 American diabetic adults over age 20 needed lower-limb amputations (60% of amputees in the U.S. are diabetics).
FDA Asks Doctors to Review Diabetic Amputation Risk Factors Before Prescribing Invokana
The FDA’s black box warning includes several diabetic amputation risk factors that healthcare professionals should consider before prescribing Invokana, including:
- A history of prior amputation
- Peripheral vascular disease (PVD and PAD are the same condition)
- Neuropathy
- Diabetic foot ulcers
Essentially, if you or your doctor notice any of the above symptoms while taking Invokana, discontinue the drug’s use immediately. Many physicians find black box warnings incredibly helpful since they call out more significant drug side effect risks. However, these warnings cannot prevent patients from being prescribed potentially harmful medications — especially for individuals that are already taking them.
What You Can Do
If you or a loved one took Invokana and suffered serious health complications (including diabetic amputation), talk to your doctor. Since Invokana doubles your risk of diabetic amputation, ask about alternative treatment options that have fewer potentially serious side effects.
And if you required one or more diabetic amputation procedures while taking Invokana, you may be eligible for financial compensation. Since Janssen failed to warn consumers about Invokana’s increased amputation risks, multiple lawsuits are now underway. To see if you may qualify for a cash settlement, complete your free Invokana claim evaluation form today. An experienced attorney will contact you to discuss your compensation options and next steps for getting the justice you deserve.
Related: Invokana Alternatives That Lower Blood Sugar in Type 2 Diabetics
Mandy Voisin
Mandy Voisin is a freelance writer, blogger, and author of Girls of the Ocean and Star of Deliverance. As an accomplished content marketing consultant, mom of four and doctor's wife, Mandy has written hundreds of articles about dangerous drugs and medical devices, medical issues that impact disabled Americans, veterans' healthcare and workers' compensation issues since 2016.