Newspaper headlines are warning that eating “a ham sandwich a day” increases the risk of type 2 diabetes – but experts say it’s not that simple.

The study, which included nearly 2 million people in 20 different countries, found it was linked to both red and processed meats, such as steak, bacon and sausage.

But doctors say that although the research is well done, its findings are nuanced and should not cause fear or panic.

He says it’s sensible to limit intake, in line with healthy dietary guidelines, but the study doesn’t mean meat should be removed from the menu.

In this research, The Lancet Diabetes & Endocrinology The study published in the journal has an unavoidable limitation — it cannot prove that eating meat causes diabetes, as it is impossible to rule out other potential risk factors, such as what other foods the study participants ate and their lifestyles.

Dr Duane Mellor, of the British Dietetic Association, said: “The authors tried to control for other risk factors associated with an increased risk of developing type 2 diabetes, including being overweight, smoking, alcohol, low vegetable intake.”

But a lack of data meant they could not take into account the effect of family history, insulin resistance or waist circumference, which are more strongly associated with diabetes.

“So it is possible that the increased risk associated with processed and red meat intake may be a result of these other confounding factors,” Dr. Mellor said.

Such studies also rely on participants telling the truth and accurately remembering what they ate.

The study found that eating two slices of ham (50 grams; 1.7 ounces) or a small (100 grams) steak each day could be risky.

The findings were less clear regarding chicken and other white meats.

The NHS is advising people already eating more than 90g (cooked weight) of red or processed meat a day to reduce this to 70g, as experts believe eating too much processed meat may cause bowel cancer.

The International Agency for Research on Cancer ranks it in the same risk category as tobacco smoking and asbestos.

Processed meat has been modified for flavor or to increase shelf-life.

The chemicals and methods used, such as smoking, processing, or adding salt or preservatives, may be a factor.

And while meat is a good source of protein, vitamins and minerals, it also sometimes contains very high amounts of saturated fat, which has been linked to higher blood-cholesterol levels, a risk factor for coronary heart disease.

Lead researcher Professor Nita Forouhi, from the University of Cambridge, said: “Our research provides the most comprehensive evidence to date about the link between eating processed meat and unprocessed red meat and a higher risk of future type 2 diabetes.”

“This supports recommendations to limit the consumption of processed meat and unprocessed red meat to reduce the incidence of type 2 diabetes in the population.”

In type 2 diabetes, blood sugar levels rise because the body produces too little of a hormone called insulin — or the insulin that is made doesn’t work properly.

Risk factors include:

• being obese or overweight
• high blood pressure
• Ethnicity
• family history

• Milk
• Cheese
• Eggs
• fortified yeast extract, such as Marmite
• Fortified breakfast cereals
• Fortified soy products