Incidence of CKD and mortality in youth-onset T2D vary across populations

A systematic review conducted by researchers at the Chinese University of Hong Kong (CUHK) has shown that the incidence of chronic kidney disease (CKD) and mortality in youth-onset type 2 diabetes (T2D) vary across Western and some Asian populations, highlighting an urgent need for long-term studies in other regions.

“As an important chronic condition in children and adolescents, T2D is associated with grim prognosis … [Research] on short-term and long-term clinical outcomes of this population [ie, youth-onset T2D] has been steadily growing,” the researchers wrote. “Our study aims to assess the incidence of CKD, cardiovascular disease [CVD] and mortality in people diagnosed with T2D at the age of <20 years.” [Diabetes Res Clin Pract 2022;doi:10.1016/j.diabres.2022.110030]

The systematic review included 17 retrospective and prospective observational cohort studies (sample size range, 96–4,141) that reported the incidence or prevalence of CKD, CVD or mortality in patients with T2D onset at the age of <20 years. Of these, 14 studies were conducted in North America and Europe, and one each was conducted in Australia, Japan and India. At study enrolment, the patients’ duration of diabetes was 0–8.3 years, and the follow-up duration was 1–12.6 years.

Results from 15 studies showed incidence rates of 12.4–114.8 per 1,000 person-years for albuminuria, 10–35.0 per 1,000 person-years for macroalbuminuria or proteinuria, and 0.4–25.0 per 1,000 person-years for end-stage kidney disease (ESKD). These findings indicate variations in incidence of renal complications in youth-onset T2D across countries and regions.

Of five studies comparing incident CKD in youth-onset T2D vs type 1 diabetes (T1D), two revealed that T2D was associated with a higher incidence of CKD than T1D (hazard ratio, 4.0 and 20.1). In one study, the incidence of ESKD was higher with T2D vs T1D (incidence rate ratio, 4.6). Two studies demonstrated no between-group difference in CKD or proteinuria.

“Youth-onset T2D has a more aggressive natural history of kidney complication vs T1D,” the researchers suggested. “Youths with T2D may have other metabolic risk factors [such as obesity, hypertension and dyslipidaemia] associated with kidney complications.”

Four studies showed crude mortality rates of 1.0–6.6 per 1,000 person-years. The most common causes of death were infection, external causes and kidney disease. “Premature complications and mortality due to long duration of diabetes and ageing will have devastating impacts on the population [with youth-onset T2D],” the researchers commented.

However, studies on incident CVD were limited. In two North American studies of patients with mean duration of youth-onset T2D of <2 years, the annual incidence rates of CVD were <0.1 percent or not reported. “Long-term observational studies are required for assessing cardiovascular outcomes in these individuals,” the researchers noted.

“In youth-onset T2D, high-quality studies on the development of diabetes complications, particularly CVD, are scarce,” they concluded. “To further confirm these findings, we need large-scale studies with longer follow-up in different populations.”

The incidence of youth-onset T2D has been increasing in developed countries. [Morb Mortal Wkly Rep 2020;69:161-165; Diabet Med 2018;35:737-744] A Hong Kong registry reported a crude incidence rate of youth-onset T2D of 3.42 per 100,000 persons/year in 2008–2017, which was significantly higher than that in 1997–2007 (1.27 per 100,000 persons/year; p<0.001). Common comorbidities at presentation included dyslipidaemia (35.3 percent), hypertension (22.5 percent) and microalbuminuria (12.8 percent). [Pediatr Diabetes 2021;1-6]