The role of type 2 diabetes in other chronic diseases

A new study found that type 2 diabetes plays a key role in the development of co-morbidities such as heart failure and chronic kidney disease, particularly in its early stages

Type 2 diabetes (T2D) remains one of the fastest growing diseases in the world. A 2021 Lancet study forecast that the condition will affect an estimated 1.3 billion people by 2050.

While the recent development of ground-breaking new obesity medicines will hopefully help quell rising T2D diagnoses, there is no doubt that increasing numbers of people eating unhealthily and living more sedentary lives remain at risk of developing diabetes.

Adding to this global disease burden is the fact that T2D often occurs with other chronic conditions like blood pressure, heart failure and chronic kidney disease.

But how quickly individuals with T2D accumulate multiple chronic diseases, and how the rate of progression varies by age, is not fully understood. A new study aimed to shed light on these areas. Danish researchers explored how T2D influenced the rate of chronic disease development in 502,368 UK Biobank participants.

It found that T2D plays a critical role in chronic disease accumulation, particularly during the early stages. “Concerningly, people with T2D showed faster progression to diseased states compared to those without the condition,” explained lead author Dr Jie Zhang from the Steno Diabetes Center Aarhus in Denmark.

“This acceleration was observed across all age groups, with the pattern being more pronounced in middle-aged adults. Our results highlight T2D as a key factor in multi-morbidity and underscore the need for stage-specific care strategies tailored to different phases of chronic disease development.”

The average age of the participants at enrolment to the study was 58 years, and around 46 per cent were men. Researchers used health records to track health outcomes over 15 years on average, during which time 47,725 (9.5 per cent) participants were diagnosed with T2D, and the number of diseases they subsequently developed (among 80 long-term chronic conditions) were counted.

To calculate the pace of chronic disease development, researchers used multistate models to compare transition rates between groups with equivalent total disease. For example, they compared how long it took someone with T2D and one additional chronic condition to acquire a third condition, versus how long it took someone with two non-T2D chronic conditions to develop another condition. This approach isolates the role of T2D by ensuring both groups start with the same total number of chronic conditions.

Individuals with T2D consistently experienced higher transition rates (more rapid progression) between multiple disease stages. For example, for individuals with two chronic conditions, those with T2D as one of them progressed to a third condition at a rate of 5.7 per cent per year, compared to 3.5 per cent per year for those with two non-T2D conditions. This corresponds to people with T2D continuously facing a 60 per cent higher risk of a new disease being diagnosed compared to those without T2D.

When analysing differences in the risk of multimorbidity progression at different ages after controlling for sex, education and body mass index (BMI), the study found that participants with T2D in the younger age groups (40-55 years) showed a faster rate of disease accumulation than their counterparts in older age groups.

“This finding underscores the need for early intervention in midlife to slow multimorbidity progression,” said Dr Zhang. “The reasons why participants with T2D in the younger age groups appear to progress more quickly requires further research.

“The most important message from our findings is that, among individuals with the same number of chronic conditions, those with T2D experience a faster progression to additional condition, compared to those without T2D.

“This reveals the dynamic role of T2D, as the association between T2D and disease progression was strongest at early stages and gradually diminished with advancing multimorbidity.”

The study was presented at this year’s annual meeting of The European Association for the Study of Diabetes (EASD) in Vienna, Austria.

The authors acknowledge several limitations to the research, including that risk factors such as socioeconomic status, smoking, diet and clinical measures were only assessed at the start of the study, which does not take into account for any changes during follow-up.

They also note that detection bias may influence the findings, as individuals with T2D receive more frequent medical monitoring, potentially leading to earlier identification of additional chronic conditions.

Additionally, as a descriptive study, it cannot establish causal relationships, and they say that future research should investigate underlying mechanisms. Participants in the UK Biobank are also known to be healthier and more educated than the general population, so the findings might not apply to people from other populations.

The study comes as the World Health Organisation (WHO) added GLP-1 therapies such as liraglutide, semaglutide and tirzepatide to its Essential Medicines List for T2D in high-risk groups in September. In December, WHO released its first guidelines on the use of these medicines in the treatment of obesity as a chronic, relapsing disease. The conditional recommendations part of a comprehensive approach that includes healthy diets, regular physical activity and support from health professionals.

“Obesity is a major global health challenge that WHO is committed to addressing by supporting countries and people worldwide to control it, effectively and equitably. Our new guidance recognizes that obesity is a chronic disease that can be treated with comprehensive and lifelong care,” said Dr Tedros Adhanom Ghebreyesus, WHO Director-General.

“While medication alone won’t solve this global health crisis, GLP-1 therapies can help millions overcome obesity and reduce its associated harms.”