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Prediabetes is defined as a blood glucose level higher than normal but below the diagnostic threshold for diabetes. It is a common health problem which is often under-diagnosed and largely overlooked due to poor awareness of the condition. The Chinese University of Hong Kong (CUHK)’s Faculty of Medicine (CU Medicine) analysed clinical data of two million adults in Hong Kong to examine the long-term health impact of prediabetes. Results showed young people at an average age of 20 with prediabetes have a 90% lifetime risk of developing diabetes, together with higher risks of  cardiovascular diseases. Details of the study have been published in international medical journals PLoS Medicine and The Lancet Regional Health – Western Pacific.

Prediabetes means a higher risk of developing Type 2 diabetes in the future

According to the International Diabetes Federation, 300 million people have prediabetes worldwide. This high-risk condition can progress to Type 2 diabetes if not detected and managed early. However, due to the silent and non-urgent nature of prediabetes, it is often overlooked in the community, including by healthcare workers.

Using anonymised data provided by the Hong Kong Hospital Authority, the Diabetes and Endocrinology Research Team at CU Medicine determined the lifetime risk of diabetes in two million adults with or without prediabetes between 2001 and 2019. For an average 20-year-old person, the lifetime risk of diabetes was 66%. This probability increased to 90% in those with prediabetes at age of 20, who were projected to spend 33 years, or 52% of their remaining lifespan, living with diabetes.

Professor Andrea Luk, Professor of the Department of Medicine and Therapeutics at CU Medicine, and lead investigator of the research, remarked, “Young people born in recent years appeared to be more affected than those born in earlier years, directly reflecting the adverse health effects of nutritional transition and a sedentary lifestyle. Given that diabetes is associated with many major diseases, such as ischaemic heart disease, stroke, kidney disease and cancer, early progression to diabetes can be extremely devastating for a person, especially if affected when young.”

The risk relationships between major clinical events and prediabetes are stronger in younger people

The research team further explored other direct health consequences of prediabetes. In a related analysis of the same surveillance dataset, they observed that prediabetes independently predicted increased risk of various major clinical events (see details in Table 1 in appendix). Importantly, the excess risks were the most pronounced among younger individuals. For example, the relative risk of cardiovascular disease was 67% in people aged 20-39 with prediabetes, versus 3% in those aged 80 years or above.

Professor Ronald Ma, Professor of the Department of Medicine and Therapeutics at CU Medicine noted, “Although these estimates in our young people are alarming, in a post-hoc analysis of a diabetes prevention study conducted in the United States, younger adults achieved greater improvement in body composition and cardiometabolic markers from lifestyle intervention than older adults.”

Current guidelines recommend intensive lifestyle modification for people diagnosed with prediabetes. Certain blood-glucose lowering medications had also been proven to prevent diabetes in these high-risk individuals, who often need to control other metabolic risk factors, notably obesity, high blood pressure and high blood cholesterol.

Professor Juliana Chan, Chair Professor of Medicine and Therapeutics at CU Medicine, said, “Previous clinical trials have shown that both lifestyle interventions and medications are effective in normalising blood glucose and preventing or delaying the onset of diabetes. However, due to low awareness regarding the adverse health impacts of prediabetes, despite its highly preventable nature, prediabetes is often not diagnosed or, if diagnosed, is not acted upon. Our findings have shed new light on the clinical ramifications of this diagnosis and drawn public attention to the importance of regular blood glucose screening even in young people, especially if they have a family member with diabetes or other risk factors.”

Other important contributors to the study include Zhang Xinge, PhD candidate, and Dr Wu Hongjiang, Research Assistant Professor in the Department of Medicine and Therapeutics at CU Medicine.