Diagnosed by Ants
Long before blood tests, doctors noticed diabetes by what came out of the body. An Egyptian manuscript from about 1500 BCE mentions "too great emptying of the urine", and the Ebers papyrus even recommends a drink for it.
The name came later. The term "diabetes", meaning "to pass through", was first used around 230 BCE by the Greek Apollonius of Memphis. The word literally means "a passer through" or "a siphon", describing how water seemed to run straight through patients.
The most vivid clue came from India. Around the sixth century CE, Indian physicians called the disease *madhumeha*, or "honey urine", noting that the urine attracted ants. Earlier, around 400-500 CE, the Indian physicians Sushruta and Charaka had already identified two separate types, one linked with youth and one with being overweight.
Too Much Sugar in the Blood
Diabetes is a group of common endocrine diseases defined by blood sugar that stays too high. It happens either because the pancreas makes too little of the hormone insulin, or because the body's cells stop responding to insulin properly.
The classic warning signs are known as the three Ps: polydipsia, or excessive thirst; polyuria, or excessive urination; and polyphagia, or excessive hunger. Unexplained weight loss and blurred vision often come with them.
The tricky part is that many people feel nothing at all. About half of those affected may be asymptomatic. Type 1 tends to appear suddenly, while type 2 creeps in slowly, and people can go for years without symptoms while the damage builds.
Type 1, Type 2, and the Difference
There are two major types, and they work very differently. Type 1 is an autoimmune condition: the body's own immune system attacks the beta cells in the pancreas that produce insulin. It is usually present from birth or develops early in life, and the most common treatment is insulin injections.
Type 2 is far more common, accounting for more than 95% of cases. Here the body becomes resistant to insulin, so glucose stays in the bloodstream instead of being absorbed by cells. It is managed with medicines such as metformin, semaglutide or tirzepatide, together with lifestyle changes.
There are other forms too. Gestational diabetes can appear during pregnancy and normally clears up shortly after delivery. Diabetes can also result from genetic conditions, diseases of the pancreas, or certain medications.
The 1921 Breakthrough and What Is at Stake
For almost all of history there was no effective treatment. That changed in the early 20th century, when the Canadians Frederick Banting and Charles Best isolated and purified insulin in 1921 and 1922.
Treatment matters because untreated diabetes damages blood vessels, both large and small. It doubles the risk of cardiovascular disease, and about 75% of deaths in people with diabetes are due to coronary artery disease. It also raises the risk of stroke.
The small vessels suffer too, in the eyes, kidneys and nerves. Damage to the retina, called diabetic retinopathy, is the most common cause of blindness in people of working age. Treatment brings its own risk: hypoglycemia, blood sugar that drops too low, is a recognised complication of insulin therapy.
A Fast-Growing Global Picture
The number of people living with diabetes has risen sharply. It climbed from 200 million in 1990 to 828 million in 2024. That already exceeds earlier projections that 783 million adults would have it by 2045.
Diabetes now affects one in seven adults worldwide and causes some two million deaths each year. More than half of the people who have it are unaware of their condition. Rates are similar in women and men.
The rise is steepest in low- and middle-income countries, where diabetes is now the seventh leading cause of death. The global cost of diabetes-related healthcare is estimated at 760 billion US dollars a year.
