The warning signs of type-2 diabetes may be detectable 20 years before the disease is diagnosed, researchers say.
Elevated fasting blood sugar levels and insulin resistance were seen in people years before they developed pre-diabetes, often a pre-cursor to type-2, a study found.
The findings suggest interventions to stop the disease in its tracks should begin far earlier in life, authors say.
Another study found type-1 diabetes may be misdiagnosed after the age of 30.
The Japanese study, carried out between 2005 and 2016, looked at the body mass indexes (BMIs), fasting blood sugar levels and insulin sensitivity of 27,000 non-diabetics, who were aged between 30 and 50 and were mostly men.
Insulin resistance occurs when cells of the body do not respond properly to the hormone insulin and can lead to a variety of health problems.
A higher BMI is a well known risk factor for type-2 diabetes.
The study followed participants until they were diagnosed with type-2 diabetes, pre-diabetes – where blood sugar levels are abnormally high – or the end of 2016, whichever came first.
Over the study period, 1,067 new type-2 diabetes cases were diagnosed.
Researchers found these people had had increased fasting blood sugar levels and insulin resistance, along with higher BMIs, up to 10 years before diagnosis.
A similar pattern was observed in those who went on to develop pre-diabetes – the same kind of warning signs, albeit to a lesser degree, had been detectable more than a decade before they were diagnosed.