An observational study suggests that implementation of prescribing guidelines for patients with type 2 diabetes may be contributing to recent declines in mortality in this group.

While the prevalence of type 2 diabetes is changing, there is also increasing evidence of the potential effectiveness of a range of therapies, including lipid-lowering, anti-hypertensive therapy, and blood glucose lowering, especially with metformin. This study aimed to determine whether increasing use of these therapies was associated with changes in early mortality in patients with type 2 diabetes. The authors used data from the UK GPRD to carry out a cohort study involving 197 UK GP practices. Eligible patients were aged 30 and over, and had type 2 diabetes first diagnosed between 1996 and 2006. The data was analysed to determine age-specific incidence of type 2 diabetes by study year, drug prescriptions for statins, antihypertensive drugs, and oral hypoglycaemic drugs split into metformin and sulphonylureas. Outcomes included all-cause mortality and prescription of hypoglycemic, lipid-lowering, and antihypertensive drugs.

Over the study period, there were around a million people aged 30 and over registered in the database: of these, there were 48,579 with a first diagnosis of type 2 diabetes. There were marked changes in prescribing for the drugs of interest over the study. Prescription of statins within 12 months of diagnosis increased between 1996 and 2006, from around 5% in 1996 (men 5.1%, women 4.9%) to over 60% in 2005 (men 71.0%, women 63.5%). There were also increases in prescriptions for antihypertensive drugs acting on the renin-angiotensin system (RAS) from around 20% in 1996 (men 21.5%, women 19.4%) to around 50% in 2005 (men 54.6%, women 45.5%), and for metformin (1996, men 15.8%, women 19.1%; 2005, men 42.8%, women 45.5%), Prescriptions for sulphonylureas declined.

All cause mortality within the first 24 months after diagnosis fell for both men and women. For men, the decline was 47%, from 47.9 per 1,000 person-years for 1996 diagnosis to 25.2 for those diagnosed in 2006; in women the decline was 26% due to their lower absolute rate (37.4 in 1996 to 27.6 in 2006). Analysis found that prescription of statins and drugs acting on the RAS before and after diagnosis, and prescription of metformin after diagnosis were all associated with lower mortality.

Based on their analysis, the authors conclude that in this population, there has been a significant reduction in early mortality after diagnosis of type 2 diabetes. This has been coincident with increases in prescribing of drugs that are recommended for use in these patients. While it is likely that other factors are also important, widespread implementation of more effective prescribing may have contributed to the reduction.