Increasing prevalence of type 1 diabetes in older age may be a good sign

The increasing burden of a chronic disease is usually a bad sign for both health providers and the general population, but the results of our study are one of the exceptions (doi:10.1136/bmj-2023-078432). Counterintuitively, the increasing prevalence of type 1 diabetes mellitus (T1DM) we found among people aged 65 and older is a good sign.1 It suggests that substantial improvements have occurred in the care that people with diabetes receive and provides cause for optimism for all people with a diagnosis of T1DM, especially younger patients.

Many public health professionals might recall the classic illustration used in epidemiology classes to describe the burden of a disease, with the prevalence of a disease likened to a pond, the incidence to a waterfall that feeds the pond, and the mortality or cure to a brook that leaves the pond. The fullness of the pond (prevalence) is decided by both the inflow (incidence) and the outflow (mortality or cure). For lifelong diseases without a cure, it is a bad thing if this pond becomes too dry, as it means that an increasing number of people are dying from the disease, but it is also a bad thing if this pond becomes too full, as it means that there are more people with a new diagnosis of the disease.

Traditionally, T1DM is considered a disease with potential to severely shorten life expectancy.23 The increasing prevalence of T1DM among people aged 65 and older that we found in our research shows that an increasing number of people with T1DM are surviving to older age. According to our findings, T1DM is no longer a severely life shortening condition thanks to medical improvements over the past three decades.

Given the reduction in mortality, the morbidity associated with T1DM becomes more important. We also wanted to know if people with T1DM were experiencing fewer complications. To answer this question, we calculated disability adjusted life years (DALYs), which combine both mortality and morbidity. We found that there had been a decrease in DALYs from T1DM among older people, but DALYs were decreasing at a less pronounced speed than mortality, meaning the reduction in mortality was greater than it was for morbidity.

This finding should prompt us to improve the current guidelines aimed at reducing morbidity from T1DM, which still lack targeted recommendations for older people, particularly on how to provide continuous care.456 Continuous care requires healthcare staff to understand both T1DM and ageing. For example, according to our research, a high fasting plasma glucose level was the major contributor to DALYs, showing that optimal blood glucose control remains challenging among older populations. The difficulty of optimal blood glucose control among people with T1DM lies in how insulin doses need to be dynamically adjusted depending on a person’s daily nutrient intake, dietary patterns, insulin sensitivity factors, daily activity, and more. Blood glucose levels become even more challenging to control for older people because of their changing metabolism and other factors associated with ageing.

In clinical practice, doctors would rather see hyperglycaemia than hypoglycaemia in older people, because hypoglycaemia leads to immediate adverse outcomes, including unconsciousness, falls, brain damage, and cardiovascular events. Trying to tightly control diabetes can increase stress for both older patients and their care givers. The principle should be to aim for normoglycaemia without the risk of hypoglycaemia.7 Therefore, for optimal blood glucose control among older people with T1DM, we suggest an active, not tight, control of blood glucose level. We suggest that guidelines should place an emphasis on capacity building, nutrition education, and training for older people with T1DM and their care givers.

We must also consider inequalities between countries with a different sociodemographic index in the burden of T1DM among older people. Notably, we found that the highest prevalence of T1DM among older people was in high income regions and countries, whereas the highest DALYs were in lower income regions and countries. While mortality was substantially decreasing among older people with T1DM in high income countries, it decreased at one 13th of the speed for their counterparts in middle income countries. Updated guidelines will need to tackle inequalities among older people with T1DM in settings with limited resources, raise awareness of the importance of timely management and blood glucose control, and reduce silent deterioration among older patients.7

Our study extended the current understanding of the increasing global burden of T1DM by honing in on the trend in older people with T1DM and found that they are generally living longer with fewer complications. Based on this, we advocate for urgent attention to management strategies with regards to ageing and T1DM, investment in health resources and training for staff, and targeted guidelines for older people with T1DM.