A lack of medical staff training means diabetics are taking pills rather than being encouraged to lose weight, research claims.
A study says doctors and nurses are handing out pills to diabetics rather than recommending they take more exercise.
Some 36% of people with type 2 diabetes are put on medication within the first month of being diagnosed, the research said.
Guidelines say people with type 2 should be given advice on managing their weight and taking up exercise before medication is prescribed.
Dr Rob Andrews, a researcher on the study, being presented at Diabetes UK's Annual Professional Conference in Glasgow, blamed a lack of staff training, too few dieticians and government targets on managing diabetes.
He said: "If you don't give patients the chance to understand their disease and don't let them try and control it with diet and exercise, evidence shows that for all the time they have diabetes, they don't focus on diet and exercise.
"We know that during diagnosis is the time when people may actually take action on those things."
A total of 2.25 million people in the UK are diagnosed with type 2 and another 500,000 are thought to be undiagnosed.