Population studies estimate that type 2 diabetes reduces life expectancy by around six years on average, while for type 1 diabetes the reduction is typically between ten and sixteen years depending on age at diagnosis. Those are the figures, stated without embellishment.
And now for what is almost never said at the same time: they are averages from broad populations, calculated using people diagnosed decades ago, when continuous glucose monitoring, modern insulin analogs, and closed-loop systems did not exist. They do not describe someone diagnosed today, and certainly do not describe any particular person.
This article places each figure alongside its study, population, and date, because the headlines you will find when searching for this contradict one another only in appearance. Since the answers vary greatly depending on the type, it is helpful to understand the differences between type 1 and type 2 diabetes before reading the tables.
Why the figures you find do not match
If you search for this topic, you will see headlines mentioning 6 years, 10, 13.5, 14, 16, and 18. None of them is lying. They are measuring different things:
| Figure commonly cited | Where it comes from | Who it describes |
|---|---|---|
| 6 years less | Emerging Risk Factors Collaboration and UK Biobank | Average for all people with type 2 diabetes, regardless of age at diagnosis |
| 14 years less | Same analysis | Type 2 diabetes diagnosed before age 30 |
| 3–4 years less | Same analysis | Type 2 diabetes diagnosed around age 60 |
| 16 years less | Swedish National Diabetes Register | Type 1 diabetes diagnosed during childhood |
| 10 years less | Same registry | Type 1 diabetes diagnosed between the ages of 26 and 30 |
| 13.5 years less | JDRF T1D Index | Global average for type 1, including countries with limited access to insulin |
The difference between 3 and 16 years is no one's error: it is the real gap between a diagnosis at 60 and a diagnosis at 8. When someone throws out an isolated figure without saying which group it belongs to, the figure means nothing.
Type 2 diabetes: age at diagnosis matters most
The largest analysis to date combined individual data from 19 high-income countries from two sources, the Emerging Risk Factors Collaboration and the UK Biobank: 96 cohorts, 1,515,718 participants, and 23.1 million person-years of follow-up.
The risk of death from any cause, compared with someone without diabetes, clearly declines as diagnosis occurs later:
| Age at diagnosis | Mortality risk compared with the population without diabetes |
|---|---|
| 30–39 years | 2.69 times higher |
| 40–49 years | 2.26 times higher |
| 50–59 years | 1.84 times higher |
| 60–69 years | 1.57 times higher |
| 70 years or older | 1.39 times higher |
In terms of years of life, each decade earlier in diagnosis is associated with around 3 or 4 fewer years of life expectancy. Someone diagnosed at 40 loses an average of around 10 years; someone diagnosed at 60, between 3 and 4.
The underlying reason is simple: it is not diabetes itself, but the length of exposure. The more years a person lives with elevated blood glucose, the more opportunity cardiovascular and kidney complications have to develop. And unlike the age at which you were diagnosed, that is modifiable.
Type 1 diabetes: what the registries say
The main reference is the Swedish National Diabetes Register, with 27,195 people with type 1 diabetes compared with 135,178 controls matched by age, sex, and county, followed for an average of ten years. The results, published in The Lancet, rank the loss by age at diagnosis:
- Diagnosis before age 10: 18 fewer years of life expectancy for women and 14 for men.
- Diagnosis between ages 26 and 30: around 10 years less.
- People diagnosed as children live an average of 10 years less than those diagnosed as adults.
A previous Scottish study, involving around 25,000 adults with type 1 diabetes followed between 2008 and 2010, estimated that at age 20–24, men had 45 years of life remaining and women 47, compared with 56 and 61 years in the general population of the same age. Its authors highlighted something that remains true today: life expectancy in type 1 diabetes had improved substantially compared with earlier estimates.
The figure of 13.5 years that appears in many headlines comes from JDRF’s T1D Index and is a global average. It includes countries where access to insulin is not guaranteed, so it is not the figure applicable to Spain.
The detail that changes how everything above should be read
Look at the dates. The Swedish registry included people diagnosed between 1988 and 2012, with follow-up through 2012. The Scottish study measured outcomes from 2008 to 2010. The cohorts in the Emerging Risk Factors Collaboration began, on average, between 1961 and 2007.
In other words: practically everyone in those studies lived through most of their diabetes before continuous glucose monitors, hybrid closed-loop systems, and several classes of drugs that are standard today existed. The data are robust, but they describe medicine that is no longer current.
This is not empty consolation. It is why the researchers themselves insist that the figures are revised upward every time they are recalculated using more recent cohorts, and why no one with good judgment will tell you how many years you have left based on a table.
How much proper diabetes treatment adds
Here is the fact that almost never accompanies the alarming headlines, despite being supported by the same level of evidence. The Steno-2 study randomly assigned 160 Danish people with type 2 diabetes and microalbuminuria to conventional or intensive multifactorial treatment for 7.8 years, then followed them until they had completed 21.2 years.
The intensive-treatment group survived a median of 7.9 years longer than the conventional-treatment group, and the onset of cardiovascular disease was delayed by 8.1 years, with a 45% reduction in relative risk.
Compare the two figures calmly. Type 2 diabetes reduces life expectancy by about 6 years on average. Intensive treatment of all risk factors for less than eight years added nearly 8. These figures cannot be subtracted using a rule of three, because the populations are different, but they show the scale of the issue: what you do about the disease matters just as much as having it.
And “intensive treatment” didn’t mean anything exotic. It meant treating glucose, blood pressure, cholesterol, and kidney function at the same time, with specific targets, instead of monitoring only blood sugar.
What’s in your hands
None of these levers is new, and all are supported by evidence:
- Treat cardiovascular risk, not just glucose. Most of the years lost are due to cardiovascular and kidney disease, not hyperglycemia.
- Do not leave years undiagnosed. Nearly one-third of people with diabetes in Spain do not know they have it, and that time counts as exposure.
- Seek remission if the diagnosis is recent. In type 2 diabetes, there is a real window in the first few years: we explain it in the article on type 2 diabetes remission.
- Stay active and manage your weight. These are the two variables that most affect insulin resistance and cardiovascular risk at the same time.
- Do not smoke. Combined with diabetes, it increases vascular risk more than any other avoidable factor.
- Attend your checkups. Eye exams, kidney function, feet, and blood pressure checks detect complications while they can still be slowed.
If you have just received the diagnosis and this has frightened you
It is a normal reaction, and it happens to almost everyone. It is worth separating two things: a population statistic and a personal prognosis. The first describes what happened on average to hundreds of thousands of people in circumstances different from yours. The second does not exist in any table, and only your medical team can estimate it by looking at your individual case.
If the fear takes hold and affects your day, that can be treated too. Bringing it up during an appointment is not going off script: screening for emotional distress is part of diabetes care standards.
This article presents the results of population studies for informational purposes and is not a prognosis or a substitute for medical assessment. If you have concerns about your situation, the conversation that helps is with your doctor.
Sources
- Emerging Risk Factors Collaboration. Life expectancy associated with different ages at diagnosis of type 2 diabetes in high-income countries. Lancet Diabetes & Endocrinology
- Steno-2 Study. Years of life gained with intensive multifactorial intervention, 21 years of follow-up
- Swedish National Diabetes Register. Early-onset type 1 diabetes and life expectancy (The Lancet)
