Four million people have diabetes—probably

"Number of people with diabetes reaches over 4 million"

Diabetes UK, 5 January 2016

Several news outlets have picked up on the latest set of figures issued by Diabetes UK, which say that four million people now have diabetes.

That seems about right, although half a million of those counted haven't been diagnosed. So there's a bit of uncertainty about that part of the figure.

The charity's analysts arrived at the four million figure by combining five different sets of numbers.

Each of England, Scotland, Wales and Northern Ireland give separate figures for people aged 17 and over recorded by their GP as having diabetes. Those added up to almost three and a half million patients last year.

But Diabetes UK reckons there are plenty more undiagnosed cases of Type 2 diabetes—some 549,000.

This estimate is one the charity has produced itself. Data from government body Public Health England seems to support the idea that there are around this number of undiagnosed cases, though we weren't able to fully verify this when we last wrote about this subject.

That's not to say that 549,000 isn't a legitimate estimate. It's just less concrete than the GP registers of diagnosed patients. By definition, it's probably impossible to be certain of how many unknown cases exist.

When Diabetes UK last produced these figures in August 2015, its estimate of undiagnosed cases was higher, at 590,000.

We can confidently say that at least three and a half million people had diabetes last year, and that this number is rising.