While depression and diabetes have been linked previously, the study from Hong Kong examined the effects of an early diagnosis of type 2 diabetes on hospitalization over time.
While the connection between type 2 diabetes (T2D) and depression is well-known, the specific burdens of people diagnosed with T2D before they turn 40 have received less attention. A review in Lancet Endocrinology found that not only was the number of young adults with T2D “dramatically increasing,” but that in this population, “evidence is accumulating that young-onset type 2 diabetes has a more aggressive disease phenotype, leading to premature development of complications,” which the authors said could bring “a future public health catastrophe.”1
Now, results from Hong Kong bring more data to that grim warning. Published today in the Annals of Internal Medicine,2 the study finds that those diagnosed with T2D before age 40 were twice as likely to be hospitalized by age 60 as those diagnosed later in life.
When these younger adults with T2D went to the hospital before age 40, the study found, more than a third of the time it was for a mental health condition. As they aged, those diagnosed at young ages were 6 times more likely as those diagnosed later to be hospitalized with renal problems and twice as likely to be hospitalized with cardiovascular issues.
“This large study highlights the evolution of hospitalization during the long course of [young onset diabetes],” the authors from the Chinese University of Hong Kong and the University of Toronto write. “With an excess burden of mental illness in early adulthood and cardiorenal complications later in life. This costly burden is an urgent call for policy makers, payers, patients, and healthcare providers to take action and address this unmet need.”
Diabetes has long been associated with depression, in part because the task of managing it can take a toll on those who live with the disease. In recent years, however, there has been more interest in the common biological origins of T2D and depression.3 The authors call for more work in this area and greater effort to increase use of organ-protective drugs, citing the fact that young adults with T2D are more likely to miss work due to their health condition.
The researchers followed nearly 423,000 people from the general population (46.3% were women), as well as 20,886 from a diabetes registry (47.2% women). They used records from the Hong Kong Diabetes Surveillance Database and the Hong Kong Diabetes Registry, examining groups of people diagnosed before they turned 40, those diagnosed from age 40 to age 59, and those diagnosed at age 60 and beyond. Patients from the population records were followed an average of 6 years, while those from the registry were followed a little more than 10 years on average. Hospital days were calculated by matching health record data from the Hong Kong Hospital Authority.
In those diagnosed in early adulthood, 36.8% of the hospital bed days before turning 40 were due to mental illness, which the authors found “could not be explained by antipsychotic medication miscoding or secular effects.”
After age 60, cardiovascular causes were the most reason for hospitalization. Compared with those diagnosed with T2D after age 40, by the time they reached age 60, those diagnosed in young adulthood were hospitalized at 6.7 times the rate of those with normal-age onset for renal causes, 3.7 times as often for diabetes-related causes, and 2.1 times as often for cardiovascular disease.
“On the basis of the observed hospitalization rates, we estimated that the patient diagnosed with [young-onset diabetes] would spend nearly 100 days in the hospital by his or her 75th birthday,” the authors wrote. Those with early-onset diabetes generally had poor glycemic control and were more likely to use insulin; intensified control of modifiable risk factors “was associated with a one-third decrease to 65 days.”
By contrast, delaying the onset of T2D past a person’s 40th birthday reduced the number of hospital days to 47.
The economic burden of diabetes (both type 1 and type 2) has received increased attention in the United States. The American Diabetes Association’s study, the Economic Costs of the Diabetes in the US in 2017, found that the average medical expenditure for people with diabetes is $16,750 per year of which $9600 is due to diabetes.4 It is estimated that medical costs are 2.3 times higher for those with diabetes than if they did not have the disease.
The authors of the Hong Kong study do not directly address the possibility of preventing T2D in younger adults. The National Diabetes Prevention Program (DPP), based on a 2002 study by the National Institutes of Health,5 has been shown to reduce the progression to T2D by 58% among those with prediabetes, a condition characterized by having elevated blood glucose levels but not enough to be classified as having diabetes. While long-term data from the National DPP show that those who enrolled in the lifestyle change program eventually progressed to T2D at nearly the same level as those who took metformin, it took them much longer to get there.
However, the Hong Kong authors call for “an integrated system” to identify those who have been diagnosed with T2D early in adulthood, for a “comprehensive assessment of physical and psychological health, followed by optimization of cardiometabolic risk factors and individualized care to improve quality of life and reduce the effects of long-term complications on patients, their families, employers, and the healthcare system.”