Age of type 2 diabetes associated with cardiovascular & mortality risk
The journal Circulation has published a new study. The study compared the age of diagnosis with type 2 diabetes and adverse cardiovascular disease (CVD) risk. The authors claim an earlier onset of diabetes increases the risk of suffering adverse cardiovascular events e.g. stroke, heart attack.
The researchers collected data from the national diabetes register in Sweden (where the study was conducted) and studied cardiovascular outcomes over time.
They therefore had access to important data points such as age, weight, body mass index, blood pressure, blood lipids etc at diagnosis.
It was a large scale study comparing over 200,000 people with diabetes against over 1.3 million people without diabetes. Only patients diagnosed with diabetes within 10 years were included to help isolate the effect of the disease without existing complications skewing the data. Diabetes and non diabetes patients were matched closely so external variables were minimised.
Results of the study
The study found an inverse relationship between the age of diagnosis with type 2 diabetes and body mass index. Patients diagnosed under 40 years old had a higher BMI of 8 units on average (e.g. 30 or 38kg/m2) when compared to patients diagnosed between 71-80. In other words, people diagnosed earlier in life tended to be more overweight. This implies earlier diagnosis is much more lifestyle related than when diagnosed later in life.
Patients diagnosed under 40 years old also had higher HbA1c values compared to those diagnosed later in life. This means average glucose levels were higher in these people.
Complication rates were significantly reduced with each increasing decade of diagnosis from the age of 40 onwards. In fact, people diagnosed over the age of 80 were at no increased risk of any complications.
The authors also analysed years of life lost amongst the age groups. If diagnosed at 15 years old people died approximately 12 years earlier. People diagnosed at age 45 lost 6 years of life. Those diagnosed at 65 years lost 2 years of life. No additional loss of life was seen in people 80 years or above.
It’s worth considering this didn’t capture data like quality of life. Aside from an early death, when looking at the data we can see people with diabetes are more prone to Cardiovascular Disease. Developing such complications will of course effect quality of life. Therefore, the true effect of early diagnosis may not be totally reflected here.
Here’s a graph demonstrating the results:
This graphs show the risk associated with each risk factor and age of diabetes diagnosis. The further to the right the dots are the higher the risk factor. If the dot is on or left of the line it means the risk is no greater or less compared to non diabetes patients.
We can see people diagnosed below 40 are over 3 more times likely to develop cardiovascular disease, have a heart attack (AMI) and suffer a stroke. They are over 4 more times likely to suffer heart disease or heart failure. They are also over twice as likely to die.
What I like about this study
The study used real world data and so this wasn’t a just a lab finding. They therefore had access to important data points such as age, weight, body mass index, blood pressure, blood lipids etc at diagnosis. This allowed them to profile patients and compare age groups against one another in relation to disease risk.
It was a large scale study. One area a lot of studies fall down on is the ability to recruit sufficient numbers. In large scale studies like this we can be more confident the findings truly reflect what is going on.
It also appears to confirm what we find in real world practice. Often such studies are born out of the anecdotal findings of healthcare professionals. However, without confirming such theories in well controlled large scale studies, theories remain just that. This is why we tend to negotiate more relaxed glucose targets in the elderly population because they have less time to live with the disease (without sounding too morbid).
I like the fact it compares loss of life data. Not because I’m some sicko. Instead it is because sometimes when comparing relative risk data we don’t look at the actual numbers. For example, if the risk is 1 in 10,000000. A relative risk of 2 or being twice as likely only increases the actual figures to 2 in 10,000000. Not great if you’re that individual but this isn’t enough to trigger significant investment into preventing that risk. Whereas hard numbers like loss of life show us the true burden of the disease risk.
What I don’t like about this study
The study was not a systematic review. This means the authors didn’t compare their results against other studies. To my knowledge these findings replicate most other well designed large scale studies.
Also because it was large scale the data appears reliable.
The study is also observational. In other words, the researchers are only watching from the sidelines. If you’ve read any of my other blogs on dietary data you’ll know the flaws of observational studies. The greatest flaw is true cause and effect cannot be established.
There could be a number of other factors at hand contributing to the outcomes of the study. A tool for minimising this effect is to separate participants and compare sub groups. For example, separating out all the people who smoke and comparing the remaining indivudals. The problem with this is as you separate more additional variables fewer participants are compared against each other hindering the power of the study.
Despite a couple of flaws I think this is a really good study. It matches what we see in practice and highlights the need for early intervention in patients diagnosed earlier in life.
If support isn’t offered early to patients the disease may worsen leaving these patients at an increased risk of complications. This is obviously terrible for the patients but will also have an impact on the health care economy. More complication rates require more medication and more funding. In a healthcare system which is operating on an already stretched budget, prevention really should be the name of the game.
We know a large part of type 2 diabetes care is lifestyle related. In my opinion this highlights the need for early and specialist input from folks like myself. Hopefully, with more studies like this we can begin to increase funding for preventative healthcare. This could help patients before they become high risk and begin suffering with complications of disease.
Hopefully sharing such data with patients can act as a catalyst for those high risk patients to make lifestyle changes. A good intervention is only as good as the patients willingness to do it. Therefore, having good evidence to show what can happen if they don’t take action could be a powerful motivator. This isn’t to scaremonger but to offer transparency.
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Sattar, N., et al., 2019Age at Diagnosis of Type 2 DiabetesMellitus and Associations With Cardiovascular and Mortality Risks Findings From the Swedish National Diabetes Registry. Circulation. 2019;139:00–00. DOI: 10.1161/CIRCULATIONAHA.118.037885