“Is my insulin still good?”

I have asked myself this question so many times over my three decades with type 1 diabetes — when I notice that no matter how much I dose, it isn’t lowering my blood sugar. When it feels like I’m just injecting water.

Sometimes I have left my insulin vials outside the fridge for weeks, or it was delivered on a hot summer day and sat outside on the front porch for hours while I was at work — without adequate ice packs (and despite the fact that the package was supposed to be delivered to my office).

Or there were times at the drugstore when the pharmacist couldn’t find my insulin in their cooler, but rather found it sitting out at room temperature for an unknown period of time. Could this be the culprit?

This frequent uncertainty over insulin quality is scary stuff to those of us who rely on this medication to survive. We spend outrageous amounts of money for our prescription insulin, and we trust these Food and Drug Administration (FDA)-cleared medications are being handled properly as they travel to a local pharmacy, or to our doors via a mail-order supplier.

A new study published in April offers some reassurance that insulin being sold at U.S. pharmacies is, in fact, up to required standards of safety and efficacy once it reaches people with diabetes, like us. That finding counters an earlier controversial study that raised doubt and pointed to supply chain issues negatively impacting insulin quality.

“During such an unprecedented time, it’s more important than ever for people with T1D to feel safe. This study reaffirms our confidence in the safety and effectiveness of insulin products,” said Dr. Aaron Kowalski, president and CEO of JDRF, who lives with type 1 diabetes himself.

In October 2018, the trio of JDRF, American Diabetes Association (ADA), and the Helmsley Charitable Trust announced they’d be jointly funding a new study to analyze insulin purchased at pharmacies. A University of Florida team took on this one-year study, led by Dr. Timothy Garrett. They examined nine insulin formulations with varying action times in five U.S. regions using different potency testing methods.

Published in the ADA’s Diabetes Care journal, the study found that insulin purchased from U.S. pharmacies is consistent with product labeling and has the required level of consistency and active insulin within the purchased vials.

An article published in late April 2020 details the study and points out that the nine different formulations included short, fast, and long-term analogue and human insulin. The insulin was both in vials and pens and came from four pharmacy/grocery retail chains within the five U.S. regions. The research included 174 total samples.

Per the FDA-required labeling and the established U.S. Pharmacopeia standards, insulin vials and pen cartridges must contain 100 units per mL (+/- 5 U/mL). This study found that all of the purchased insulin met that requirement.

The study authors concluded that their work “represents an important independent analysis seeking to identify potential failures in the cold supply chain emanating from the geographic region and/or pharmacy that could affect the quality and reliability of insulin products at the point-of-patient purchase across the U.S.”

“We believe our study, thus far, provides an affirming answer to the question of the viability of the U.S. insulin supply at the point of retail pharmacies,” it states.

Researchers also noted that this is a single year of research, and it will be expanded during a second study phase measuring any potential seasonal variations in reported insulin activity.

This research is a direct response to an earlier study in late 2017, which was met with criticism from the scientific community, but raised concerns within the diabetes patient community about insulin safety.

Published on December 21, 2017, that study looked at older insulin brands, R and NPH (made by Lilly and Novo Nordisk), as the predecessors to analogue insulins that debuted in the later ’90s.

The experts who led this study included Dr. Alan Carter of the non-profit MRI Global research group and a pharmacy professor at the University of Missouri-Kansas City, and Dr. Lutz Heinemann, a San Diego-based expert on insulin and emerging biosimilars.

Researchers randomly picked up 18 vials of insulin and stored them in a research lab at the appropriate temperatures, before discovering that the concentrations weren’t adequate. Insulin vials and cartridges are required by the FDA to contain 95 U/ml of insulin when they’re sent out by the manufacturer. Regulators also require proper handling and temperatures in order to maintain quality.

But when Carter and his team examined the insulin they’d purchased, the vials ranged from 13.9 to 94.2 U/ml, with a mean of 40.2 U/ml. No vial was at the minimum FDA-required standard of 95 U/ml. Here’s a link to the full paper.

“Bottom line is we owe those with diabetes our best efforts in finding as many answers as possible,” Dr. Carter told DiabetesMine shortly after his study was published. “Assuming the insulin is always good is a nice place to be, until it’s not…”

Carter says the supply chain may have an impact on insulin quality that could affect glucose control.

As to how they reached those study results, Carter says they were “acquired using new technologies that are very precise and have been used for detecting intact insulin in plasma but have not been validated by any regulatory agency for measuring intact insulin concentrations in vials or pens. More work is needed to explore the reasons why the intact insulin was detected at reported levels… using this approach. Perhaps a different way may be better and still needs to be determined.”

In the years that followed, the researchers worked with the Diabetes Technology Society to dig deeper, especially with more modern insulins that exist on the market today. That included organizing a panel of diabetes experts, patients, government agency officials, and insulin manufacturers to discuss the issue and explore the insulin supply chain more fully.

Surprisingly, the ADA responded to that initial 2017 study by issuing a statement that basically dismissed the results and essentially implied, “trust us, this isn’t an issue.”

The ADA specifically called out the extremely small sample size and the methodology used, pointing out that it (ADA) consulted “clinical and biochemistry experts” and found the results were inconsistent with their own findings and real-world examples.

Additionally, the ADA noted that it consulted with insulin manufacturers and saw no reason to suspect they are at any fault based on quality control procedures mandated by the FDA.

“Based on these findings, we have no reason to believe that the results of Carter et al.’s study reflect the actual potency of human insulin widely available at retail pharmacies in the United States,” their lead physician wrote at the time. “We strongly urge patients to talk with their doctors and pharmacists about any concerns they have with their insulin or diabetes treatment plan.”

This ruffled feathers, especially among those who believe the ADA’s acceptance of Pharma funding influenced what it said and did.

Of course, as we patients know, no one can deny that sometimes insulin goes bad. If and when that happens, we need to be aware of:

Pharmacies: They don’t all have blanket policies on what medications are returnable, be it a local walk-in pharmacy or a mail-order company. You would need to explore their return/refund rules, which can often be found online. If you attempt to return insulin, a pharmacy may argue, but you can fight back. Your doctor can contact the pharmacy to attest that your batch of insulin is ineffective.

Insulin Makers: They have troubleshooting programs in place and are pretty good at replacing potentially bad insulin. For example, each of the three big insulin makers, Eli Lilly, Novo Nordisk, Sanofi, offer information for dealing with faulty insulin.

Regulators: Yes, the FDA also regulates the supply chain from the manufacturer to the supplier, where it travels before ending up in the patients’ hands. The agency has a whole Drug Supply Chain Integrity division where patients can read up on all the laws and requirements and also report suspected issues. There’s also a MedWatch reporting system online.

In a perfect world, the high prices we’re forced to pay for insulin would guarantee that what we’re getting is always up to par. But sometimes things go wrong, whether in manufacturing or during transit.

We’re glad to see a trio of leading diabetes organizations investing in research on this topic so that there is finally some hard science in place to identify and address any systematic problems causing compromised insulin before it reaches the people who need it to survive.


Mike Hoskins is Managing Editor of DiabetesMine. He was diagnosed with type 1 diabetes at age five in 1984, and his mom was also diagnosed with T1D at the same young age. He wrote for various daily, weekly and specialty publications before joining DiabetesMine. Mike lives in Southeast Michigan with his wife Suzi and their black lab, Riley.