Monday, June 29, 2009

A New Problem With Insulin: Cancer.

Followers of this blog will note that my approach to the management of Type 2 diabetes is different then currently recommended guidelines. Unlike current recommendations which seem to push insulin after the failure of two older oral agents (which are known to fail), I recommend that multiple agents be used, reserving insulin as a last resort. I have blogged before about my concerns with insulin (The Problem With Insulin , The Problem with Insulin- Part 2 ). While life-saving for all type 1 diabetics and many type 2 diabetics, insulin causes many problems including the need to frequently monitor finger stick glucose, costs, inconvenience, weight gain, and hypoglycemia which can lead to death.

However, a new concern regarding glargine insulin (trade name Lantus) seems to be emerging. This press release best explains it. In summary, a recent study confirmed earlier findings between increased rates of cancer in diabetes taking glargine insulin and regular insulin, in particular, a doubling risk of breast cancer.

Why might this be true?
Human and even porcine insulin has a long track record of safety. However, glargine insulin is different in that it is not "natural" but a manufactured insulin, specifically modified to last longer. While insulin has been used for decades, glargine has only been used since 2000. Other reasons to consider this more than just a concern include that the findings are reproduced in multiple studies of tens of thousands of people, and that the finding seem dose dependent. In other words, the higher the dose of glargine one takes, the higher the risk of cancer. In order to know for sure, we need a randomized, controlled trial of thousands of patients to prove this is the case. This is exactly what the European Diabetes Association is calling for. However, those findings will not be available for years.

Why be concerned?
Most guidelines for type two diabetes recommend that long acting insulins be started first, and most clinicians usually start with the synthetic, glargine type of insulins. In fact, the preferred regimen for insulin in type 2 diabetics by most endocrinologists is a combination of a long acting insulin like glargine given once a day with very short acting insulins (lispro) at meal times. This approach, called basal-bolus, is supposed to mimic what the pancreas naturally does. Though I am glad that the European endocrinologists have raised concern and are calling for more data, I find it interesting that more alarm has not been raised, particularly here in the US. One very poorly done study which has now been proven to be false, caused so much uproar that people simply stopped taking Avandia. Yet, study after study shows a compelling and dose responsive relationship between glargine and cancer, and there seems to be little in the press.

What should you do?
If you are on Lantus, don't stop!!!! Please discuss this with your doctor first. There are other options other than Lantus, and even with an increased cancer risk, Lantus still may be the best option for you. If you are diabetic, but not yet on insulin, first do everything you can to avoid this. First and foremost, diet and exercise are key and critical. If that doesn't work, in addition to lifestyle changes, consider using multiple pills before resorting to insulin. If injections are needed, talk to your doctor about the incretin mimetics, like Byetta as alternatives to insulin. Studies of shown that in patients who failed diabetes pills, Byetta performed similarly to glargine in controlling diabetes but with less hypoglycemia and weight gain.


Christine said...

I've been on R alone, R + Lantus, Novolog + Lantus, Novolog + Levemir, and I've pumped R, Humalog, Apidra, and Novolog.

Novolog + Lantus was by far the best control I got prior to pumping. My control wasn't even close to as good on Levemir. I told my endocrinologist this, which got met with a "Yeah, Levemir sucks, Lantus is the only good long acting insulin."

And it's true. If the studies are more strongly validated, I feel bad for type 1s not on pumps.

Dr. Matthew Mintz said...

I am guessing you are a type 1 diabetic, for which Lantus may be a necessary medication. Lantus is a good insulin and should be used when appropriate. Though the possible cancer risk is some cause for concern, every medicine has risks and benefits, which need to be weighed. My issue is with the "experts" who seem to want to push many type 2 diabetics to insulin (usually Lantus) when they fail one or two older drugs which are known to fail. There are many, many more options to try for these patients before going to Lantus.

Anonymous said...

why not use a drug like Levemir, and forget about Lantus, and avoid this increase in IGF-1 altogether? Wouldn't that be a better option than even dealing with this issue?