Type 2 Diabetes More Prevalent Than Type 1 Among Adolescents in Some Areas

Focus on Diabetic Nephropathy

Diabetic kidney disease is the leading microvascular complication of type 2 diabetes in adolescents. It is associated with rapid progression and poor prognosis. The natural history begins with hyperfiltration: A consequence of obesity and impaired glucose tolerance. Structural renal changes can be detected as early as 1.5 years after diagnosis.

The second stage is characterized by a reduction in the glomerular filtration rate. At this stage, “the structural changes in the kidney are typical but often present,” said Pinhas-Hamiel, making this period critical for reducing risk factors.

In TODAY, the cumulative incidence of diabetic nephropathy was 54.8%. The prevalence at inclusion was 8%. In SEARCH, after 8 years, the prevalence of diabetic kidney disease was 19.9% among adolescents with type 2 diabetes vs 5.8% among those with type 1 diabetes. A pre-analysis revealed that the overall prevalence of macroalbuminuria among 730 children and adolescents with type 2 diabetes was 3.8%. The ages at diagnosis of type 2 diabetes ranged from 6.5 to 21 years, and the duration of the disease varied from diagnosis to 15 years after.

Diabetic retinopathy was present in 50% participants in the TODAY study at age 25 years (ie, after 12 years of disease). In SEARCH, 56% young patients had diabetic retinopathy after 12.5 years of diabetes. In addition, in the same study, the prevalence of peripheral neuropathy, assessed after 8 years, was 22% among adolescents with type 2 diabetes vs 7% among those with type 1 diabetes.
 

Cardiovascular Autonomic Neuropathy

A decrease in heart rate variability was observed in 47% young patients with type 2 diabetes after an average disease duration of only 1.7 years. In SEARCH, the prevalence of cardiovascular autonomic neuropathy, assessed after 8 years of disease, was 17% in adolescents with type 2 diabetes versus 12% in those with type 1 diabetes.

Overall, 7.1% participants had three complications: nephropathy, retinopathy, and neuropathy. The cumulative incidence of microvascular complications was 80%.

Moreover, A1c levels deteriorated progressively throughout the follow-up period. Approximately 45% participants had an A1c of at least 10%, and 20% were between 8% and 10%. Body mass index consistently remained between 35 and 37.5.

Young patients with type 2 diabetes exhibit endothelial dysfunction, increased carotid intima-media thickness, elevated arterial stiffness, left ventricular hypertrophy, diastolic dysfunction, and reduced maximal exercise capacity. All these factors predict cardiovascular morbidity and mortality.

In TODAY, 17 serious cardiovascular events were recorded, including four myocardial infarctions, six cases of congestive heart failure, three coronary events, and four strokes.

In an analysis of the TODAY and SEARCH studies, although the average duration of diabetes was similar, complications were more frequent among young patients with type 2 diabetes than among those with type 1 diabetes. Microvascular complications were 2.5 times more frequent, and macrovascular complications were four times more frequent.

In SEARCH, excessive mortality was observed among young adults for each type of diabetes. Differences in risk were associated with diabetes type, age, race/ethnicity, and sex. Mortality ratios were 1.5 and 2.3 for types 1 and 2 diabetes, respectively.

Women had higher mortality rates than men. Diabetes was the underlying cause of death in 9.1% cases, which was comparable to cardiovascular diseases or cancer (10.9%). According to a life expectancy model, young patients with type 2 diabetes lose about 15 years of life.