28th May 2025

Epidemiology

From 1980 to 2019 the worldwide prevalence of diabetes mellitus has almost doubled, growing from 4.3% to 8.3% (roughly 7% in the UK). The incidence of newly diagnosed diabetes has plateaued in most countries since the mid-2000s, likely due to increasing patient education and public health strategies. The most significant factors driving the rise in prevalence since this time are therefore the ageing of the global population and better outcomes for patients. These figures do not differentiate between the different types of diabetes, but it is estimated that 90% of cases are T2DM. Within the UK alone roughly one million patients are living with undiagnosed T2DM.

Several risk factors for T2DM have been identified, including:

• Increasing age
• Male sex – ratio of roughly 1.5:1.
• Obesity and inactivity – obesity is the most significant risk factor in the development of T2DM.
• Asian, Black and Afro-Caribbean ethnicity – carries a 2-4x increased risk when compared to Caucasian patients.
• Family history – there is a 2-6x increase in risk for patients with a family history of the disease. If both parents have the condition, then the overall risk for an individual stands at 85%.
• Gestational diabetes – mothers who develop diabetes during pregnancy are 7x more likely to develop T2DM later in life.
• Diet – regularly consuming sugar-rich food and drinks, with low fibre and high glycaemic index, such as sugary snacks and drinks, potatoes, white rice and white bread will significantly increase the risk of developing T2DM.
• Medications – including corticosteroids, thiazide diuretics, beta-blockers, antipsychotics and statins.
• Alcohol – moderate alcohol consumption is protective for T2DM but heavy use increases risk, both due to the effects of the alcohol itself and the increase in consumption of carbohydrates. Drinking heavily also leads to greater variability in blood sugar levels and can lead to hypoglycaemic episodes.
• Smoking – 30-40% increased risk and also independently increases the risk of cardiovascular complications of the disease.
• Metabolic syndrome – describes a pattern of common biochemical and physiological abnormalities that increase a patient’s risk of both T2DM and cardiovascular disease. The syndrome encompasses central obesity, hyperlipidaemia, hypertension, non-alcoholic fatty liver disease, atherosclerosis, insulin resistance and impaired glucose tolerance. It is thought to be a reflection of the modern shift to a more sedentary lifestyle and diet of excess.
• Polycystic ovary disease – known to cause progressive insulin resistance, which can lead to T2DM.
• Psychiatric disease – schizophrenia, bipolar disorder and depression are all associated with an increased risk.
• Sleep disorders – sleep apnoea and restless leg syndrome.