Diabetes prevalence is increasing worldwide, compounded by population growth and an ageing population.[3] In 1980, the global age-standardised diabetes prevalence was 4.3%.[3] In 2017, the global age-standardised diabetes prevalence was estimated at 8.6%.[4] Survey data of diabetes in adults does not separate type 1 and type 2 diabetes, but most cases of diabetes (around 90%) are type 2.[3] However, while the overall burden of diabetes is increasing, trends in the incidence rate of diabetes plateaued and now appear to be decreasing. Data from the US National Health Interview Survey documented that the incidence of age-adjusted, diagnosed diabetes decreased from 2007 to 2017, from 7.8 to 6.0 per 1000 adults.[5] 

Incidence and prevalence of type 2 diabetes have risen steadily since 1950, driven by increasing prevalence in obesity and being overweight.[6] In the US in 2017, type 2 diabetes had a prevalence of 8.5%.[7] In the UK, prevalence rates of type 2 diabetes increased from 3.21% in 2004 to 5.26% in 2014, and incidence rates remained stable.[8] Clinical onset is usually preceded by many years of insulin resistance and hyperinsulinaemia before elevated glucose levels are detectable.[1] 

Patients with type 2 diabetes have a very high risk of concurrent hypertension (80% to 90%), lipid disorders (70% to 80%), and overweight or obesity (60% to 70%).[9] When diabetes is diagnosed at age 40 years, men lose an average of 5.8 years of life, and women lose an average of 6.8 years of life, highlighting the importance of primary prevention of diabetes.[10] However, onset of diabetes at older ages has much less effect on life expectancy if acceptable glucose, blood pressure, and lipid control can be achieved and maintained.

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