Type 1 diabetics are at an increased rate of cardiovascular disease (CVD) with an estimated 44% of adult T1Ds dying from heart-related complications. As a diabetic, you have probably taken steps to reduce your risk of CVD by eating healthier, getting more exercise, and giving up habits like smoking. But a study recently published in Diabetic Medicine may have the T1D community adding another best practice to maintaining heart health.
Healthier Lipid Profile Associated with Pump Use
The study, which used data collected from 14,290 adolescent T1Ds from around the world, found that children on insulin pumps had more favorable blood lipid values than those on MDI.
High LDL, high nonHDL, low HDL, and high overall cholesterol are all associated with an increased risk of CVD. In diabetics, a decrease of 1 mmol/l of LDL cholesterol was associated with a 21% decrease in vascular events. While the importance of maintaining favorable lipid levels is widely known, this is the first large scale study to correlate insulin delivery method with blood lipid values.
Even after adjusting for confounding factors such as A1C, age, and the onset of diabetes, the researchers found that the LDL and nonHDL cholesterol levels were significantly higher, and HDL levels significantly lower in the group of diabetics using pump therapy compared to those on MDI.
While this study looked at a wide range of patients with varying degrees of control, a similar, much smaller study looking at 48 T1D children also found significantly more favorable lipid levels in pump users, despite similar A1C levels between the groups.
How Does Insulin Injection Method Affect Lipid Profiles?
Both these studies show a surprising but significant association between insulin therapy type and blood lipid levels. But how, when comparing two individuals with similar blood sugar control, does the method of insulin injection influence cholesterol?
At this point, researchers can only speculate.
There is some reason to believe that intensified insulin treatment can enhance the action of lipoprotein lipase. This can lead to an increase in HDL cholesterol levels in diabetics. This healthy cholesterol helps rid the blood of bad cholesterol and higher HDL values are considered a marker of heart health.
Since pump therapy tends to be more pinpointed than MDI, it would make sense that HDL levels of pump users would be higher on average than those on MDI.
The intense degree of therapy provided by pumps also helps reduce the variability of blood sugars in diabetics. Widely variable blood sugars appear to be more of a risk factor for CVD than sustained higher blood sugars. Researchers believe this has to do with the higher impact on oxidative stress markers and lipid metabolism seen during blood sugar swings. Since diabetics on pumps typically have tighter control of their blood glucose, they are less likely to suffer from high LDL and nonHDL cholesterol.
Differing Explanations and Further Research
Of course, all of the above explanations are just theories. There is also the very real possibility that real-world factors are influencing these results more than the insulin injection method.
For instance, no information was included in the data concerning the socio-economic background or lifestyle of each patient. It is possible that patients on pumps, which are vastly more expensive than the needles used for MDIs, were also from wealthier backgrounds with better access to healthcare, fresh food, and diabetes education. All of these factors would have a direct impact on blood lipid levels.
Another important factor to consider is the use of continuous glucose monitors (CGMs). CGMs have been shown to have a positive impact on both pump and MDI patients. However, the vast majority of CGM users are on pump therapy, making up about 21% of total pump users and only 5% of total MDI users. Like pumps, CGMs give the patient much tighter control and increase the time blood sugar is within a healthy range. The ability of CGMs to help diabetics maintain healthy blood glucose may even outperform insulin pumps, according to a recent study.
If pump therapy does indeed provide a patient with the ability to maintain a healthier blood lipid profile, then this is huge news that should be taken seriously by the healthcare community.
Healthy cholesterol levels are vital to avoiding unnecessary cardiac complications in a population of people who are already at increased risk of CVD. According to this study, putting adolescents directly on pumps after diagnosis could play a huge role in adding to their life expectancy.
Of course, before we can expect insurance companies and doctors to get behind this idea, we need more research into the actual cause of lipid changes in diabetics and how insulin therapy may play into it. We also need additional studies into the benefits of pump use on cholesterol in older diabetics as well as comparisons between pump and CGM therapy and overall lipid values.
For now, there does seem to be a correlation between tighter, less variable blood sugar control and healthier cholesterol levels. This is one finding that all T1Ds and healthcare professionals should keep in their mind while striving to achieve better heart health through more traditional means.