What Are the Causes of Death From Diabetes?

Heart and blood vessel disease is the single biggest killer of people with diabetes, accounting for roughly a third or more of all deaths depending on the population studied. Diabetes raises the risk of fatal heart disease by two to four times compared with the general population. But cardiovascular disease is far from the whole story. Kidney failure, stroke, cancer, acute blood-sugar crises, infections, and liver disease all claim lives, and the relative importance of each cause has been shifting over the past two decades in ways that matter for anyone living with the condition.

Heart Disease Remains the Leading Threat

Coronary artery disease is the primary cause of death in both type 1 and type 2 diabetes, carrying a two- to four-fold increase in heart disease mortality compared with people who do not have diabetes.¹ The damage is driven by years of elevated blood sugar harming the lining of blood vessels, promoting plaque buildup, and making plaques more prone to rupture. High blood pressure and abnormal cholesterol levels, which frequently accompany diabetes, accelerate this process.

One especially dangerous complication is that diabetes can damage the nerves that carry pain signals from the heart. In people with autonomic neuropathy, the prevalence of completely painless heart muscle ischemia has been found to be around 65%, compared with about 4% in those whose autonomic nerves function normally.² Without the usual warning of chest pain, a heart attack can go unnoticed until it becomes fatal. This “silent” ischemia partly explains why sudden cardiac death rates are elevated in diabetes.

Kidney Disease as a Driver of Early Death

Kidney disease does not just shorten life on its own; it amplifies almost every other risk. A large population-based study found that among people with both type 2 diabetes and kidney disease, standardized mortality reached about 31%, an absolute jump of roughly 23 percentage points over those without either condition. The researchers concluded that kidney disease predominantly accounts for the increased mortality observed in type 2 diabetes overall.³ That is a striking finding: it suggests that if you could prevent kidney damage in people with diabetes, a large share of the excess deaths would disappear.

Chronic kidney disease worsens cardiovascular risk, disturbs blood pressure regulation, and once it progresses to end-stage renal failure, it carries a mortality hazard roughly three and a half times higher than kidney disease at earlier stages.⁴ This is why routine kidney function screening is such a priority in diabetes care: catching declining kidney function early and slowing it with medication can meaningfully extend life.

Stroke and Cerebrovascular Disease

Between roughly 20% and 40% of people with type 2 diabetes develop some form of cerebrovascular disease during their lifetime.⁵ The risk, though, differs strikingly between diabetes types. A nationwide Swedish cohort study found that people with type 1 diabetes had roughly two and a half times the risk of ischemic stroke compared with matched controls, while people with type 2 diabetes had about 1.4 times the risk. Hemorrhagic stroke risk was nearly doubled in type 1 diabetes but was not significantly increased in type 2.⁶

The same study found that higher long-term blood-sugar levels (measured by HbA1c) were associated with increasing ischemic stroke risk in both types of diabetes. For hemorrhagic stroke, the picture was more nuanced: the risk climbed at a lower blood-sugar threshold in type 1 than in type 2. Either way, the practical point is clear. Poorly controlled blood sugar is directly linked to the kind of blood vessel damage in the brain that causes strokes, and strokes remain one of the top killers in the diabetes population.

Acute Blood-Sugar Emergencies

Not all diabetes deaths develop slowly over decades. Two acute crises can kill in hours or days if untreated.

Diabetic ketoacidosis (DKA) occurs when the body, starved of insulin, begins breaking down fat at a dangerous pace and producing toxic acids called ketones. DKA remains the leading cause of death in young people with type 1 diabetes, and the number of DKA episodes has actually risen over the past two decades.⁷ In children, especially in low-resource settings, DKA is the major cause of diabetes-related death.⁸ The tragedy is that DKA is almost always preventable with adequate insulin access and sick-day planning.

Hyperglycemic hyperosmolar syndrome (HHS) is more common in older adults with type 2 diabetes. Blood sugar climbs to extreme levels, and severe dehydration follows. A Japanese hospital study found that the median age of HHS patients was 75 years, and infections triggered the crisis in about half of cases. The 30-day mortality rate in patients with isolated HHS was 26%, and that figure jumped above 50% in those who also developed metabolic acidosis.⁹ Roughly 70% of the HHS patients in that study were not even on diabetes medication when the crisis struck, suggesting that undiagnosed or untreated diabetes is a major risk factor for this emergency.

When Low Blood Sugar Turns Fatal

The opposite extreme, severely low blood sugar, can also kill. Insulin and certain oral diabetes medications can push glucose down far enough to trigger seizures, loss of consciousness, and cardiac arrhythmias. Research using nationwide Korean health data has consistently found a causal link between episodes of severe hypoglycemia and both cardiovascular events and death.¹⁰ The mechanism is not a mystery: a plunge in blood sugar triggers a surge of stress hormones, which can destabilize heart rhythm and raise blood pressure sharply. For older adults living alone, a nighttime hypoglycemic episode can be fatal simply because no one is there to intervene.

Infections and Sepsis

Diabetes weakens the immune system in several ways, impairing white blood cell function and making the body slower to fight off bacteria and fungi. A large population-based cohort study found that people with type 2 diabetes had roughly 1.8 times the risk of dying from infections compared with those without diabetes. For sepsis specifically, the risk was more than doubled.¹¹ Urinary tract infections, pneumonia, and skin and soft-tissue infections are all more common in diabetes and can escalate to life-threatening sepsis faster than in people with normal blood sugar.

This vulnerability to infection has become an increasingly recognized contributor to diabetes mortality. In Korean national data, deaths from pneumonia rose noticeably in the diabetes population between 2006 and 2018, even as deaths from cardiovascular and cerebrovascular disease fell.¹² The COVID-19 pandemic brought this risk into sharp focus, but the pattern was clear well before 2020.

Cancer and Diabetes

Cancer incidence is elevated in both type 1 and type 2 diabetes, with liver, pancreas, breast, endometrial, and colorectal cancers showing some of the strongest links.¹³ The shared biology is complex but involves chronically high insulin levels (which can promote cell growth), inflammation, and obesity, which is a risk factor for both conditions.

The mortality risk from cancer is also amplified by diabetes. A large study found that men with known diabetes had about 1.7 times the cancer death rate of men with normal blood sugar, with particularly increased deaths from stomach, colorectal, and liver cancer. Women with diabetes had about 1.4 times the cancer death rate, with liver and pancreatic cancer deaths most elevated.¹⁴ When someone has both type 2 diabetes and a cancer diagnosis, their all-cause mortality rate is nearly four times that of someone with type 2 diabetes but no cancer. Among modifiable factors, smoking and low physical activity were the strongest predictors of death in this group, far outweighing blood sugar control, cholesterol, or blood pressure.¹⁵

In Australian data, cancer has actually overtaken cardiovascular disease as the leading listed cause of death among men with type 2 diabetes.¹⁶ This shift does not mean cancer is getting worse in diabetes; it means cardiovascular death rates have fallen faster than cancer death rates, leaving cancer as a bigger slice of the pie.

Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is extremely common in type 2 diabetes, affecting an estimated majority of people with the condition. Most of the time, fatty liver is silent and benign. But when it progresses to inflammation, scarring, and eventually cirrhosis, it becomes deadly. In a community-based study of patients with diabetes who also had NAFLD, liver complications were the second leading cause of death, tied with heart disease at about 19% of all deaths. Deaths included liver failure, cirrhosis complicated by liver cancer, and bleeding from swollen veins in the esophagus. Crucially, no liver-related deaths occurred among the diabetic patients without NAFLD.¹⁷

Diabetic Foot Ulcers and Amputations

Foot ulcers might sound minor compared with heart attacks and strokes, but they mark a turning point in diabetes prognosis. The nerve damage and poor circulation that cause ulcers also signal advanced disease throughout the body. Among patients who developed diabetic foot ulcers, cardiovascular disease was the cause of death in about 55% of cases, with respiratory disease a distant second at around 19%. In a small percentage of patients, the ulcer itself triggered the fatal chain of events, typically through overwhelming infection.¹⁸

A global meta-analysis found that among patients with diabetic foot ulcers, those who needed amputation had about 2.4 times the mortality risk of those who did not, and those with peripheral artery disease had nearly double the risk.⁴ The foot ulcer, in other words, functions as a canary in the coal mine. It signals that blood vessel damage has become severe enough to threaten survival.

The Shifting Landscape of Diabetes Mortality

If you look at how people with diabetes died 30 years ago versus today, the picture has changed dramatically. In the United States, vascular causes accounted for nearly half of all deaths among adults with diabetes in the late 1980s and early 1990s. By 2010-2015, that share had dropped to about a third, a decline of roughly 32% per decade in vascular death rates. Cancer death rates also fell, though more modestly. What filled the gap was a rise in “other” causes: infections, kidney failure, dementia, falls, and other conditions that gain ground as people live longer.¹⁹

Korean national data tell a similar story. Cancer was the most common listed cause of death in the diabetes population throughout the study period, accounting for roughly 28% to 32% of deaths. Cardiovascular and cerebrovascular deaths declined, while deaths from pneumonia and Alzheimer’s disease rose.¹² In Australia, the proportion of deaths from cardiovascular disease among women with type 2 diabetes fell from about 48% to 31% between 2002 and 2019, and deaths attributed to dementia rose from 2% to over 7% across all diabetes types.¹⁶

These trends reflect real progress. Statins, blood pressure medications, better surgical techniques for heart disease, and tighter blood-sugar management have all pushed cardiovascular death rates down. But the success against heart attacks and strokes has revealed the next tier of threats, conditions that now have more time to develop because patients are surviving long enough to face them.

Why Death Certificates Undercount Diabetes

Official statistics almost certainly understate how many people die because of diabetes. The reason is straightforward: when someone with diabetes dies of a heart attack, the death certificate usually lists heart disease as the cause. Diabetes gets mentioned as a contributing factor only if the certifying physician thinks to include it. One study found that among people known to have diabetes who died, only about 35% had diabetes listed anywhere on their death certificate.²⁰

The underreporting is not random. A study of fatal ischemic heart disease events in the Seattle area found that only 41% of death certificates for people known to have diabetes mentioned the condition, and the likelihood of it being included varied by patient demographics and physician characteristics.²¹ This means public health statistics that rank causes of death systematically minimize the role of diabetes. Heart disease, stroke, and kidney failure all appear as standalone killers, when in many cases diabetes was the force driving them. If every death in which diabetes played a meaningful causal role were counted, diabetes would rank far higher on national mortality tables.

Socioeconomic Disparities in Who Dies

Diabetes itself does not kill equally across society. People with less education and lower income consistently face higher diabetes-related death rates, even after accounting for age, sex, race, and body weight. One nationally representative U.S. cohort found that adults who had not finished high school had about twice the diabetes-related mortality of college graduates, and those living below the poverty line had about 2.4 times the mortality of people with the highest incomes.²²

These disparities persisted across nearly two decades of data. A separate analysis confirmed that from 1997 to 2015, adults with diabetes at the lowest socioeconomic levels consistently had higher all-cause mortality than those at the highest levels, though the patterns varied by race and ethnicity.²³ The reasons are layered: less access to preventive care, later diagnosis, difficulty affording medications like insulin or newer glucose-lowering drugs, higher rates of smoking, and fewer opportunities for physical activity all contribute. The gains in cardiovascular death prevention from statins and blood pressure drugs have disproportionately reached wealthier and better-insured populations.

The Lung as an Overlooked Target

Most people associate diabetes complications with the heart, kidneys, eyes, and nerves. The lungs get far less attention, but emerging research suggests they are not spared. The same microvascular damage that harms the kidneys and retinas can also affect the tiny blood vessels in lung tissue, and type 2 diabetes has been recognized as a significant comorbidity that worsens the course of chronic respiratory diseases like COPD and pulmonary fibrosis.²⁴ Respiratory disease ranked as the second most common cause of death among patients with diabetic foot ulcers in one study, accounting for about 19% of deaths in that group.¹⁸ The rising share of pneumonia deaths in Korean diabetes mortality data reinforces that the lungs deserve a place in any serious conversation about how diabetes kills.

1
PubMed Central. Coronary artery disease and diabetes mellitus
2
Heart. Silent ischaemia in diabetic men with autonomic neuropathy
3
PubMed Central. Kidney disease and increased mortality risk in type 2 diabetes
4
PubMed. Global mortality of diabetic foot ulcer: A systematic review and meta-analysis of observational studies
5
PubMed Central. Progress on diabetic cerebrovascular diseases
6
PubMed Central. Risk of Ischemic and Hemorrhagic Stroke in Individuals With Type 1 and Type 2 Diabetes: A Nationwide Cohort Study in Sweden
7
PubMed. Recurrent diabetic ketoacidosis and a brief history of brittle diabetes research: contemporary and past evidence in diabetic ketoacidosis research including mortality, mental health and prevention
8
PubMed Central. Risk factors for mortality in children with diabetic keto acidosis from developing countries
9
PubMed Central. Clinical features and outcomes of hyperglycemic hyperosmolar syndrome: a retrospective study at a Japanese university hospital
10
PubMed Central. Severe hypoglycemia as a preventable risk factor for cardiovascular disease in patients with type 2 diabetes mellitus
11
The Lancet Regional Health – Europe. Contribution of infection to mortality in people with type 2 diabetes: a population-based cohort study using electronic records
12
Endocrinology and Metabolism. Improvement in Age at Mortality and Changes in Causes of Death in the Population with Diabetes
13
PubMed Central. Diabetes and Cancer: Cancer Should Be Screened in Routine Diabetes Assessment
14
PubMed. Diabetes, prediabetes and cancer mortality
15
PubMed Central. Diabetes-related risk factors and survival among individuals with type 2 diabetes and breast, lung, colorectal, or prostate cancer
16
PubMed. Causes of death among Australians with type 1 or type 2 diabetes, 2002-2019
17
PubMed Central. Nonalcoholic Fatty Liver Disease Increases Risk of Death Among Patients With Diabetes: A Community-Based Cohort Study
18
PubMed Central. Mortality in Patients with Diabetic Foot Ulcers: Causes, Risk Factors, and Their Association with Evolution and Severity of Ulcer
19
PubMed. Trends in cause-specific mortality among adults with and without diagnosed diabetes in the USA: an epidemiological analysis of linked national survey and vital statistics data
20
PubMed Central. Sensitivity and Specificity of Death Certificates for Diabetes: As Good as it Gets?
21
PubMed Central. Underreporting of diabetes on death certificates, King County, Washington
22
PubMed Central. Socioeconomic status and risk of diabetes-related mortality in the U.S.
23
BMJ Open. Trends and socioeconomic disparities in all-cause mortality among adults with diagnosed diabetes by race/ethnicity: a population-based cohort study – USA, 1997–2015
24
PubMed Central. Diabetic endothelial microangiopathy and pulmonary dysfunction