By Adam Mynott, BBC News, Chennai, India
The latest figures for the prevalence of diabetes are two years old and by common medical consent hopelessly out of date.
It is estimated that up to three million people die from the disease every year, and over a quarter of a billion people are affected.
Both figures are likely to be very short of the mark.
World Diabetes Day is on 14 November and all over the planet events are taking place to draw attention to the threat of what is described as an epidemic that is out of control.
Already it kills more people than HIV/Aids and the prognosis is grim.
Patient at eye clinic
Doctors do not understand why Indians have a high rate of diabetes
India is the nation with most diabetics.
Officially there are 41 million Indians with the disease, but in Chennai, Tamil Nadu as many as 15% of the population suffer.
Elsewhere in the vast country, doctors report diabetes rates of between 9% and 14%.
So, even taking the lower of the two marks, it is clear that India, with its population of 1.1 billion, has upwards of 100 million diabetics and that figure is growing every year.