Epidemiology

Diabetes prevalence is increasing worldwide, compounded by population growth and an ageing population.[2][3]​​​ In 2000, the global diabetes prevalence in adults aged 20-79 years was estimated at 4.6%, increasing to 10.5% in 2021.[4]​ Prevalence has been rising more rapidly in low- and middle-income countries than in high-income countries.[5] Between 2000 and 2019, there was a 3% increase in age-standardised mortality rates from diabetes; in lower-middle-income countries the mortality rate due to diabetes increased by 13%.[5]

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.[2] In most countries, the incidence of diagnosed diabetes rose from the 1990s to the mid-2000s, but has been plateauing since.[3] It is thought that this trend might be owing to public health education and preventive strategies. Data are limited in developing countries and the trend in these regions might differ.[3] Clinical onset of type 2 diabetes is usually preceded by many years of insulin resistance and hyperinsulinaemia before elevated glucose levels are detectable.[1] 

People 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%).[6] Smoking prevalence among individuals with type 2 diabetes is similar to that of the general population (current smokers: 25% vs. 28%; never-smokers: 39% vs. 42%, respectively).[7]​​

The most common initial cardiovascular disease complications for those with diabetes is peripheral artery disease (16.2%) and heart failure (14.1%), followed by stable angina (11.9%), non-fatal myocardial infarction (11.5%), and stroke (10.3%).[8] On average, adults with type 2 diabetes are up to twice as likely to die of stroke or myocardial infarction compared with those without diabetes, and they are more than 40 times more likely to die of macrovascular than microvascular complications of diabetes.​[9][10][11]​ However, data indicate that adults with type 2 diabetes who optimally manage glucose, blood pressure, lipids, smoking, and weight have a risk of major cardiovascular events that is not significantly above the risk of age and sex-matched peers without diabetes.​[12]​​[13]

When diabetes is diagnosed at aged 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.[14] 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. In a large systematic review and meta-analysis, age at diabetes diagnosis was found to be inversely associated with risk of all-cause mortality and macrovascular and microvascular disease.[15]

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