Double Diabetes, Once Rare, is Now Commonplace

Double Diabetes, Once Rare, is Now Commonplace


People with type 1 diabetes are gaining more weight than ever, and it’s a problem. Over the last generation, rates of so-called “double diabetes” – the co-existence of aspects of both types 1 and 2 diabetes in a single person – have skyrocketed.

 

Obesity is on the Rise in Type 1 Diabetes

It was not so long ago that obese patients with type 1 diabetes were considered rare. Only 3% of patients enrolled in the 1987 Pittsburgh EDC study were obese, at a time when nearly 20% of the nation was. At that time, the stereotypical person with type 1 diabetes was imagined to be as thin as a rail.

Times have changed, and mostly for good reasons. The image of that unfortunate skinny patient – body ravaged by insulin deficiency, and forced to eat a monotonous “healthy” diet to reduce the incidence of acute hypo- and hyperglycemia – is thankfully now out of date. The availability of blood glucose meters, the development of modern rapid insulin, and the years of accumulated wisdom have all combined to allow those of us with the disease to live more or less just as our non-diabetic peers do. We can eat spontaneously and lavishly, with a lower risk of immediate or long-term harm. There is therefore a sense in which obesity and T1D is a combination to be celebrated, one indicating improved health, and the opportunity to recover some normalcy.

Multiple studies have now shown that people with type 1 diabetes are obese and overweight at similar rates to the general population. Some have shown that they are even more likely to be obese and overweight. And this has driven the dramatic rise in cases of double diabetes.

 

Double Diabetes

As a new and complex phenomenon, double diabetes has proven difficult to define. Precise diagnostic criteria are a matter of debate, but the condition is generally taken to mean the presence of type 1 diabetes with the addition of weight gain and marked insulin resistance, both hallmarks of type 2 diabetes.

Actual diagnoses are somewhat rare, given the novelty, but studies have shown that double diabetes could already affect as many as 25% of T1D patients. This suggests that this formerly rare condition has already become so commonplace as to barely provoke mention.

Double diabetes is considered an exceedingly difficult condition to manage, and it has intense consequences. A 2016 study found that type 1 patients with double diabetes were 167% more likely to develop heart disease, and 125% more likely to develop stroke, in addition to big increases in microvascular complications such as retinopathy and nephropathy. While it might be natural to assume that these changes were due to the lesser blood sugar control of those with double diabetes, in fact these risks increased independent of that factor.

These risks should be considered unacceptably high. Despite all of the marvelous improvements in diabetes medication and technology, even patients with well-controlled T1D are still about twice as likely to die early of any cause, particularly cardiovascular disease. Increasing those risks even further, through the development of insulin resistance and its associated metabolic dysfunctions, is a recipe for disaster.

Double diabetes can also emerge in the opposite fashion, with the symptoms of T2D preceding the development of the autoimmunity characteristic of T1D. This progression is also becoming more common. In these cases diagnosis is especially difficult. And as the lines between one form of diabetes and the other get blurred, and the two related conditions interact in ways that are too complex to tease out. It is thought, for example, that each form of diabetes tends to accelerate the development of the other. This phenomenon has been especially noted in children, given the distressing recent rise in global childhood obesity. Type 1 diabetes is mysteriously on the rise as well, and some researchers have even explained this by hypothesizing that childhood obesity can actually cause type 1 diabetes.

 

Other Factors Also Contribute to Insulin Resistance

There’s another reason to be extra careful: even if you ignore the factors generally associated with the development of type 2 diabetes, people with type 1 diabetes are still highly predisposed towards insulin resistance.  Compared to non-diabetic controls of similar age, body fat percentage, activity level and so on, patients with type 1 diabetes exhibit “profound insulin resistance.” And unlike most diabetic complications, this one isn’t caused by inadequate blood sugar control. Even those with good glycemic control that seem to be otherwise healthy can have unusual insulin resistance. There are two reasons for this, and they’re difficult to avoid.

First, injecting insulin (as opposed to creating it in your own pancreas) makes your tissues more insulin resistant. Unlike naturally secreted insulin, injected insulin bypasses the liver and goes straight into peripheral circulation. The result is that people with type 1 invariably have abnormally low amounts of insulin in the liver, and abnormally high amounts outside of it, an unnatural but necessary consequence of our insulin delivery system. And it stands to reason that the more insulin one uses, the more insulin resistance one might create.

Secondly, injected insulin tends to result in weight gain, which itself increases insulin resistance. In the landmark DCCT Trial, the group employing tight glucose management (which was experimental at the time, but is now mainstream) gained significantly more weight than the group using the conventional 1980’s treatment regimen. The reasons for this are simple to understand: insulin is the primary hormone that instructs your body to turn energy into fat, and as discussed above, we usually have too much of it circulating. Excess insulin can also promote more hunger, a feedback loop that results in overeating.

There is absolutely no question that the intensive insulin use that that allows for tight glucose control is the ultimately the healthiest treatment option. These should be considered minor downsides to what is the optimal and necessary treatment. But they are real effects that seem to meaningfully increase the likelihood that a patient with type 1 diabetes will develop type 2 diabetes.

 

Double Diabetes Prevention

There’s no mystery behind the development of insulin resistance and type 2 diabetes. As the National Institute of Health plainly says, “you are more likely to develop type 2 diabetes if you are not physically active and are overweight or obese.” If you require a high daily insulin dose (indicating a measure of insulin resistance), or have a history of T2D in the family, you may be especially at risk of the condition. An additional factor is the heavy consumption of foods that require large amounts of insulin to metabolize: carbohydrates, especially sugar and highly-processed, “empty” carbs. A low-carbohydrate diet combined with exercise may well be the best way to address all of the risk factors that lead to the development of insulin resistance and double diabetes.



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