Another Dangerously Misinterpreted Study: Insulin Doesn't Raise Cancer & Heart Disese Risk--High Blood Sugars Do

A huge, long-term UK study appears to show that for people with Type 2 Diabetes injecting insulin raises the risk of both cancer and heart disease.

The study is:

Mortality and Other Important Diabetes-Related Outcomes With Insulin vs Other Antihyperglycemic Therapies in Type 2 Diabetes
Craig J. Currie et al.  The Journal of Clinical Endocrinology & Metabolism February 1, 2013 vol. 98 no. 2 668-677

The study examined the records of 84,622 people with Type 2 Diabetes treated with 5 different drug combinations. It concludes: " In people with T2DM, exogenous insulin therapy was associated with an increased risk of diabetes-related complications, cancer, and all-cause mortality."

This conclusion is likely to lead insurance companies and physicians to deny insulin to people with Type 2 diabetes. This is tragic and very ill advised.

That is because what this study shows is a correlation between insulin use and heart disease and cancer, not causation. In fact, these results are easily explained when you understand that insulin use in people with Type 2 Diabetes in UK is a marker for long-term exposure to very high, uncontrolled blood sugars, and conclude that it is the high blood sugars, not the insulin causing the increase in mortality.

Indeed, the way that insulin is prescribed in the UK makes it so that patients aren't given insulin until they have had extremely high blood sugars for many years, and when insulin finally is prescribed it is done so in a way that does not bring blood sugars down to safe, physiologically normal levels.

So it isn't the insulin that is to blame here, it is the high blood sugars, which a great deal of research has shown cause all the classic diabetic complications as well as heart disease and cancer.

Let's look a bit more closely at how Type 2 Diabetes is treated in the UK where this study was conducted. Because the UK has a National Health Service, patients and to some extent doctors are not given choices about what treatment to use for Type 2 Diabetes. Treatment is based on the use of a rigid set of guidelines that links the treatment to long term blood sugar level. The guidelines consider 7.0% a safe and healthy blood sugar level for people with Type 2 diabetes. So no interventions occur when blood sugars are that high, though we know that level is high enough to produce all the classic diabetic complications. (You can read about the research connecting complications to blood sugar levels HERE and HERE.

At diagnosis, with A1c over 7.0%, patients in the UK are told to change their lifestyle--to exercise and eat the low fat/high carb diets that do little to lower blood sugar. Only if their A1cs continue to climb well above 7.5% are they put on oral drugs.

As we know, studies presented in the prescribing information included with diabetic oral drugs show that none of these oral drugs lower A1c more than about .5%. (I.e. from 8.5% to 8.0%.)  Patients are left on these drugs, with their A1cs in the 7-9% range for years.

Only when A1cs climb much higher are patients prescribed insulin. Unfortunately, they are not prescribed the basal/bolus insulin regimens that make it possible to get normal, physiological blood sugars. Instead, they are given only enough insulin to lower fasting blood sugars to a level that will produce A1cs in the 7-7.5% range. This basal insulin does nothing to lower the post meal blood sugar spikes that research suggests cause heart disease and promote cancer. (You can learn more about the right way to use insulin for Type 2 diabetes HERE.)

When basal insulin isn't enough, most patients are given the worst form of insulin, the 70/30 mix which combines fast and slow-acting insulin in a way that makes it impossible to cover meals tightly without risking hypos.  Patients are forced to eat high carb meals to avoid hypos with this nasty insulin blend and are unlikely to be able to lower A1c below or even to 7.0%.

Insulin under this regimen is dosed by the health professional who issues a simple guideline. As a result patients must eat a lot of carbohydrate to avoid hyping. This way of using insulin is like driving with one foot on the accelerator and one on the brake.

So patients "on insulin" at best end up with A1cs between 7.0 and 8.0%, and this occurs only  after years of exposure to the much higher blood sugars that almost certainly explain the depressing rates of heart attack and cancer seen in this study.

The outcomes of patients using insulin who use it properly are much better. But using insulin safely to normalize blood sugars require education and a lot of careful observation and adjustment of doses. It can't be done with one appointment but takes time and training. Most if not all family physicians do not understand the proper dosing of insulin. Many don't even know there is such a thing, as they refer their patients with Type 1 Diabetes  to endocrinologists. (And sadly, not all endocrinologists are familiar with how to dose insulin properly, especially not those trained before the mid 1990s.)

Used properly, the right combination of basal insulin to lower fasting blood sugars and fast-acting insulin to cover the carbohydrates in meals can make it possible to get A1cs in the 5% to low 6% range and avoid the classic diabetic complications.

To be fair to the researchers who publishsed this study, they concluded at the end of the report, "Differences in baseline characteristics between treatment groups should be considered when interpreting these results." But because they don't spell out what those differences are--that it means that the people on insulin are those with the very worst blood sugars who have lived with these very bad blood sugars for years and whose insulin did not really reverse them--this statement is very likely to be ignored.

Instead, because most U.S. physicians in general practice--the people who treat most people with Type 2 Diabetes--have almost no familiarity with the research explaining how blood sugar causes complications, this study is likely to result in fewer people with Type 2 Diabetes being given access to insulin when they need it.

Drug company marketers will use this result to pressure doctors to prescribe more  of the dangerous, heavily marketed and very expensive DPP-4 inhibitors like Januvia and Onglyza (which also cause cancer) and the GLP-1 analogs like Byetta and Victoza (the latter of which as been linked to Thyroid cancer.) Neither class of drugs lower blood sugar in people whose beta cells aren't able to secrete insulin or have been killed by very high blood sugars. These are the very people who need insulin the most.

So if doctors use this result to deny patients insulin it will, in fact,  raise the number of heart attacks and cancers over time. But it will save insurers money to deny people insulin, so expect to see this happening