People with diabetes face higher risk of sudden cardiac death

Press release European Heart Association

Ventricular Arrhythmias and Sudden Cardiac Death (SCD)
Risk Factors and Prevention

The risk of sudden cardiac death is higher both for people with type 1 and type 2 diabetes, according to a large study published in the European Heart Journal[1] today (Thursday). The increase in risk is especially noticeable among younger adults.

 

Sudden cardiac death is when someone dies suddenly and unexpectedly due to a problem with their heart. It is generally rare in young and seemingly healthy individuals.

 

The research also shows that people with diabetes have a shorter life expectancy on average, and that a proportion of this reduction is due to sudden cardiac death.

 

The research was led by Dr Tobias Skjelbred from Copenhagen University Hospital, Rigshospitalet, Denmark, and included data on the entire Danish population in 2010.

 

The researchers looked at all 54,028 deaths in the country over that year and used death certificates, hospital discharge summaries and autopsy reports to identify all sudden cardiac deaths. They found 6,862 cases.

By combining this with records of which people had type 1 diabetes, type 2 diabetes or neither, the researchers were able to compare rates of sudden cardiac death between the three groups.

 

They found that sudden cardiac death was 3.7 times more common among people with type 1 diabetes and 6.5 times more common for people with type 2 diabetes, compared with the general population. The difference in risk was greatest in younger adults, with people under 50 who have diabetes having a seven times higher risk of sudden cardiac death.

 

The research also showed that the average life expectancy was 14.2 years shorter for people with type 1 diabetes and 7.9 years shorter for people with type 2 diabetes. Sudden cardiac death was responsible for 3.4 of the years lost in people with type 1 diabetes and 2.7 in people with type 2 diabetes.

 

Dr Skjelbred said: “We found that sudden cardiac death occurs more frequently in people with diabetes across all age groups, and that sudden cardiac death has a substantial impact on the shortened life expectancy in individuals with diabetes. While sudden cardiac death risk increases with age for everyone, the relative difference is most pronounced when comparing younger people with diabetes to their peers in the general population.

“This is an observational study, meaning that we can see a link between diabetes and sudden cardiac death, but we cannot prove that one causes the other. Sudden cardiac death is challenging to predict and prevent, but these findings reinforce the importance for people with diabetes to work with their clinicians to reduce cardiovascular risk.

“There are probably several reasons behind this link, and these may differ by age. Having diabetes predisposes people to ischaemic heart disease, which is a key mechanism. In addition, diabetes-specific factors such as hypoglycaemia and cardiac autonomic neuropathy may increase the chances of an irregular heartbeat and sudden cardiac death.

 

2010

“A key limitation of this study is that it focuses on deaths in 2010, before widespread use of newer glucose-lowering therapies such as SGLT2 inhibitors and GLP-1 receptor agonists. We therefore cannot assess how these treatments may have influenced sudden cardiac death in more recent years.”

 

People who are known to have a very high risk of sudden cardiac death can be fitted with an implantable cardioverter-defibrillator, so researchers say the next step could be to identify subgroups within the diabetes population who might benefit from preventive strategies, and to study how to lower the risk for people with diabetes.

 

In an accompanying editorial [2], Dr Hanno Tan from Amsterdam UMC, University of Amsterdam, Netherlands and colleague said: “Despite significant advances in cardiovascular medicine, sudden cardiac death (SCD) remains a challenge for prevention and treatment due to its unpredictable nature and high fatality rate.

 

“Previous studies have indicated that the incidence of sudden cardiac arrest (SCA) in diabetics is elevated compared to the general population.

“In this issue of the European Heart Journal, Skjelbred et al expand upon these previous studies, furthering our understanding of the relationship between diabetes and SCD. For the first time, the extent of both loss in life expectancy due to diabetes and the contribution of SCD to this loss is quantified.

 

“Of particular interest is the finding that the diabetes-associated risk of SCD was higher among younger individuals than among older individuals. For example, the incidence rate was highest in the 30-40 year age group among type 1 diabetes patients (22.7), and in the 40-50 year age group among type 2 diabetes patients (6.0).

“[…] studies have been initiated to develop systems that may autonomously detect SCA and call the emergency number, e.g., through the use of wearables such as smartwatches. Such solutions may have particular relevance for type 1 diabetes patients, because the proportion of unwitnessed SCA events is higher in these patients than in the general population. Thus, type 1 diabetes patients may derive particular benefit from these solutions.

“[…] we may be able to reduce the burden of SCD in diabetes patients with the use of personalised treatment interventions that aim at preventing SCA and/or improving SCA treatment.”

 

ARTIKELN
Diabetes and sudden cardiac death: a Danish nationwide study

Tobias Skjelbred , Peder Emil Warming , Elijah R Behr , Lars Køber , Ulrik Pedersen-Bjergaard , Bo Gregers Winkel , Thomas Hadberg Lynge , Jacob Tfelt-Hansen

European Heart Journal, ehaf826, https://doi.org/10.1093/eurheartj/ehaf826
Published: 04 December 2025

Abstract
Background and Aims
Diabetes mellitus is associated with increased risk of sudden cardiac death (SCD). However, nationwide, unselected studies are lacking. Therefore, this study aimed to estimate the incidence rates of SCD among individuals with Type 1 diabetes (T1D) and Type 2 diabetes (T2D) and to quantify the shortened life expectancy that can be attributed to SCD.

 

Methods
The study included the entire Danish population in 2010. Sudden cardiac death cases were identified through the detailed Danish death certificates, and discharge summaries, and if performed, autopsy reports. Cox proportional hazards models were used to estimate risk of SCD in diabetes patients. Loss of life years was estimated for both T1D and T2D patients.

 

Results
Among the identified 6862 SCD cases, 97 were diagnosed with T1D and 1149 with T2D. Incidence rates of SCD were 3.7 times higher for T1D and 6.5 times higher for T2D compared with the general population. After multivariable adjustment, both T1D and T2D were independently associated with SCD. The greatest risk difference was observed in younger individuals with diabetes. Life-years lost were on average 14.2 and 7.9 years shorter for patients with T1D and T2D, respectively. A reduced life expectancy of 3.4 and 2.7 years was found to be attributed to SCD for T1D and T2D, respectively.

 

Conclusions
Individuals with diabetes displayed consistently elevated incidence rates of SCD across age groups. Further, the elevated risk of SCD in individuals with diabetes diminished with increasing age. For both T1D and T2D, SCD was an important contributing factor to shortened life expectancy.

 

From the article

Introduction
The risk of sudden cardiac death (SCD) in the general population remains an important public health challenge.1 In absolute numbers, individuals without known cardiac disease represent the largest subgroup of SCD cases.2

 

Current SCD prevention strategies focus on high-risk patients with known cardiovascular disease,3 leaving other vulnerable groups—such as persons with diabetes—relatively unaddressed. Persons with diabetes face a higher risk of SCD.4–7 However, the exact burden of SCD in this population remains largely unknown.

 

The life expectancy for individuals with diabetes is significantly shorter than that of the general population, with reductions estimated at ∼13 years for Type 1 diabetes (T1D) and 6 years for Type 2 diabetes (T2D).7–10 Individuals with diabetes experience both fatal and non-fatal cardiovascular events at younger ages compared with the general population.11 The reduction in life expectancy can be quantified as life-years lost, with a significant proportion attributable to cardiovascular disease.7However, the specific number of life-years lost that can be attributed to SCD among individuals with diabetes is unknown.

 

Our study aimed to provide precise estimates of the incidence rates (IRs) of SCD among individuals with T1D and T2D in a nationwide, unselected population. Additionally, we sought to estimate the number of life-years lost among people with diabetes compared with the general population. These objectives were achieved by utilizing a unique nationwide database of SCD cases, supplemented with health and social registry data from the entire Danish population.

 

FROM THE ARTICLE
Discussion
This nationwide study showed an association between diabetes and SCD in all age groups. Diagnosis of either T1D or T2D was associated with an increased risk of SCD when compared with the general population. Incidence rates of SCD in decedents with T1D and T2D were 3.7 and 6.5 times higher than in the general population. The IRRs were highest for young individuals with diabetes, decreasing with increasing age. The higher IRRs in younger individuals with diabetes likely reflect the low background risk of SCD in this age group, making the relative impact of diabetes appear larger. In older age groups, the effect of diabetes is less pronounced due to the growing influence of other age-related risk factors for SCD. Furthermore, individuals with diabetes have a considerably shorter life expectancy.

 

We found that the life expectancy of 30-year-old patients with T1D or T2D is 14.2 years and 7.9 years shorter than the background population. These estimates are aligned with previously published estimates for life expectancy from Sweden and the UK.8,10,18 Our study underlines that the causes of SCD are important drivers of mortality in T1D and T2D, with 3.4 years and 2.7 years of the reduced life expectancy being attributed to SCD, respectively.

 

In recent years, there has been increased focus on the interactions between diabetes and cardiovascular disease,19 and cardiovascular disease is an important driver of mortality among patients with diabetes.20Our findings add to the existing data on this topic showing that individuals with diabetes are at increased risk of SCD.4,5,21 Data from Denmark show that the IRs of SCD in the young have been reduced dramatically since the year 2000.22 However, prevalence rates of T2D are rising dramatically both in Denmark and many other countries worldwide.23,24 Globally, over 500 million people are living with diabetes and is expected to rise to ∼780 million persons by the year 2045.23 In Denmark, the prevalence of T2D increased from 1% to 4.5% from 1996 to 2016.24 Consequently, prevention of cardiovascular disease and SCD in persons with diabetes is a challenge that will grow larger in the future.

 

The associations between diabetes and SCD are well established, but the underlying mechanisms are complex. Multiple pathways have been proposed. Most often, the link between diabetes and SCD will be related to the presence of underlying ischaemic heart disease. Furthermore, patients with diabetes are also predisposed to developing heart failure, atrial fibrillation, and stroke. Diabetes is also a risk factor for developing renal disease, which is also associated with elevated risk of SCD.25 Cardiac autonomic neuropathy (CAN) has also been proposed as a potential pathway for the link between diabetes and SCD.26 Cardiac autonomic neuropathy leads to changes in the effect of the autonomous nervous system on the heart and thus also on the cardiac ion channels responsible for the cardiac impulse. Further, glycaemic control has been proposed as a possible marker for risk stratification of SCD in diabetic patients. In a Dutch study of sudden cardiac arrest in non-diabetic individuals, higher levels of glycated haemoglobin were associated with increased rates of ventricular fibrillation, independent of cardiovascular comorbidities.27Similarly, in a nested case–control study of patients with diabetes from the USA, increases in glycated haemoglobin levels were associated with increased risk of SCD.28 To summarize, more research is needed to uncover mechanisms of SCD in individuals with diabetes beyond ischaemic heart disease to improve risk stratification and prevention in the future.

 

One such mechanism is hypoglycaemia. Although there is a benefit of glycaemic control in patients with diabetes in reducing risk of cardiovascular events,29 this benefit carries an increased risk of hypoglycaemia, when glucose-lowering treatments include insulin and sulfonylureas.30,31 Acute hypoglycaemia elicits sympathoadrenal activation, increases cardiac workload, and is associated with QT prolongation and hypokalaemia, all potential arrhythmogenic factors that might promote malignant arrhythmias leading to SCD.32–34Furthermore, hypoglycaemia results in prolonged proinflammatory and prothrombotic responses that may contribute to the development of CVD. Accordingly, hypoglycaemia is strongly associated with a broad range of adverse cardiovascular outcomes.30,35 In a subgroup analysis of our data, we found that the IRs of SCD were highest among individuals treated with insulin, irrespective of age and diabetes type (see Supplementary data online, S7). Rates were intermediate among individuals treated with a combination of insulin and oral antidiabetic drugs and lowest among those receiving only oral antidiabetic drugs. Investigating hypoglycaemia in a post-mortem setting is difficult due to the rapid changes in blood glucose that occur shortly after death. It can therefore not be ruled out that hypoglycaemia is the cause of death in some autopsy-negative SCD cases. It is noteworthy that the SCD cases had a high prevalence of hospitalization for severe hypoglycaemia and that among the SCD cases with Type 2 diabetes, the prevalence of insulin therapy was high, suggesting a greater hypoglycaemic burden among the SCD cases.

 

In our cohort, we observed a notable burden of hypoglycaemia among SCD cases with diabetes. Specifically, 37% of those with T1D and 7.2% of those with T2D had a history of hospital contact for hypoglycaemia (Table 2). Moreover, there was a high prevalence of other diabetic complications among SCD cases with diabetes. These findings suggest that the burden of diabetes-related complications, particularly hypoglycaemia, may play a role in SCD risk and could provide useful information for future risk stratification efforts in this population.

 

We observed that the overall IR of SCD is higher among patients with T2D than T1D. This can partly be explained by the higher average age in the T2D group, as SCD IRs rise rapidly with increasing age. In our Cox proportional hazards model, the population was split into three age intervals: <50, 50–75, and 75+. Moreover, in our Cox proportional hazards model, the HR of SCD in individuals with diabetes decreased with increasing age (Table 4): from a HR of ∼7 in patients with diabetes under 50 years to a HR of ∼1.5 in those over 75 years of age. Previous studies of this topic have found approximately a two-fold increased risk, when adjusting for relevant covariates.5,36,37 We find similar estimates when analysing the whole population, but this method violated the proportionality assumption and did not accurately describe the risk in the underlying data. Therefore, providing three HRs more accurately described the increased risk of people with diabetes compared with the background population (Table 4).

 

Unravelling the association between diabetes and SCD is complex for several reasons. First, individuals with diabetes are at increased risk of developing cardiovascular disease as a complication of their condition.19 Second, cardiovascular diseases such as ischaemic heart disease and heart failure may serve as mediators in the pathway between diabetes and SCD. Third, a predisposition to T2D may coincide with a predisposition to other conditions, including cardiovascular disease, due to shared genetic or environmental risk factors. Given these complexities, we present three multivariable adjustment models to better characterize this relationship (Table 4). While extensive adjustment helps minimize residual confounding, it is important to recognize the potential for overadjustment by including variables that may be both a confounder and a mediator on the causal pathway. Such adjustment could underestimate the true total effect of diabetes on the risk of SCD.

 

The risk of SCD in both T1D and T2D is similar. Our findings suggest that there is a large potential gain in improving prevention of ventricular arrhythmia in individuals with diabetes. The age at which SCD occurs is an important consideration, and we show that this group has a significantly shortened life span compared with the background population. The average age of SCD cases among patients with T1D was 14.2 years younger than the non-diabetic cases (Table 2). In addition, 3.4 years of a total of years reduced life expectancy in T1D can be attributed to SCD. Therefore, efforts to prevent the causes of SCD in this group may yield the largest results.

 

 

FROM THE ARTICLE

Conclusions
This is the first nationwide, unselected study to describe the IRs of SCD in individuals with T1D and T2D. We demonstrate that the IRs of SCD are 3.7 times higher for T1D and 7.5 times higher for T2D compared with the general population. The disparity in SCD IRs and risk is most pronounced among younger age groups. Additionally, individuals with diabetes experience reduced life expectancy, with a significant proportion of life-years lost attributable to SCD. These findings highlight the need to deepen our understanding of the diabetes-specific mechanisms that contribute to ventricular arrhythmias and SCD.

 

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