Age at diagnosis in US adults with type 1 diabetes
Many cases of adult-onset type 1 diabetes are diagnosed after age 30, study says
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In the general population of more than 1.3 million American adults, 37% of patients reported being diagnosed with Type 1 diabetes after 30 years ; Men and racial/ethnic minorities were diagnosed later compared to women and non-Hispanic white adults.
A recent study of patients with type 1 diabetes (T1D) in the United States found that a significant proportion of type 1 diabetes diagnoses occur in patients over 30 years of age. The findings, published in Annals of Internal Medicine , are consistent with previous studies suggesting that more than half of type 1 diabetes cases develop in adulthood.
Misdiagnosis is common in cases of adult-onset type 1 diabetes, and those who are misdiagnosed with type 2 diabetes (T2D) do not receive adequate care for the management of type 1 diabetes, the authors noted . . Estimates based on emerging data indicate that up to 62% of type 1 diabetes cases develop in patients older than 20 years, 2 and the current study aimed to provide information on the burden of early-onset type 1 diabetes. adulthood among the general US population
"Type 1 diabetes is generally considered a childhood disease," said study author Elizabeth Selvin, PhD, MPH, co-director of the Cardiovascular Disease Epidemiology Training Program at the Johns Hopkins Bloomberg School of Public Health, in a statement. written. "Our results suggest that a substantial portion of cases are diagnosed in adulthood. Adult-onset type 1 diabetes often presents with mild symptoms, and it can be challenging to distinguish it from type 2 diabetes in those cases. ".
Selvin and colleagues at the Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland, used data from the National Health Interview Survey (NHIS) to explore the age distribution of type 1 diabetes diagnosis in the United States. They combined all NHIS survey cycles that included diabetes subtype data (2016, 2017, 2019, 2020, 2021, and 2022), covering approximately 1.3 million American adults.
NHIS interviews collected data on patient demographics and medical information, and patients with diabetes reported type of diabetes, insulin use, and their age at diabetes diagnosis. The study included people at least 18 years old who reported being diagnosed with type 1 diabetes and currently using insulin.
From the general population, 947 people with type 1 diabetes were identified. The mean age at diagnosis and the percentages of patients diagnosed after 20, 30 and 40 years were estimated, and analyzes of the general population were performed, as well as of demographic and clinical characteristics. Overall, the mean age at the time of completing the NHIS was 49 years, 48% of the population was female, and 73% were non-Hispanic white.
In the general population, 37% of patients reported being diagnosed with Type 1 diabetes after 30 years. Although the distribution of age at diagnosis of type 1 diabetes peaked around age 15 and was generally younger, the median age at diagnosis was 24 (IQR, 12-40). years.
Men were diagnosed at a mean age of 27 years, while the mean age of diagnosis among women was 22 years. Among racial/ethnic minorities, the average age at diagnosis ranged from 26 to 30 years, compared to 21 years among non-Hispanic white adults. Men and racial/ethnic minorities also had higher rates of diagnosis after age 30 and higher mean ages of diagnosis.
“Consistent with our findings, previous studies suggest that more than half of type 1 diabetes cases develop in adults. “We extend existing research by characterizing age at diagnosis in a nationally representative sample and documenting variation between race/ethnicity and clinical characteristics,” the authors wrote.
They noted that the best way to identify adults who are at high risk for type 1 diabetes is unclear and that traditional markers such as body mass index are now less useful because obesity has become common in the type 1 diabetes population. 1. Therefore, new risk stratification tools could be useful for the diagnosis of Type 1 diabetes.
According to Selvin, the factors driving differences in average age at diagnosis between men and women and between racial/ethnic groups have not yet been elucidated.
"It is not entirely clear why racial and ethnic minority groups tend to be diagnosed later. This may reflect disparities in access to care, including access to specialists such as endocrinologists and diabetes clinics," Selvin said. "The finding that women tend to be diagnosed later compared to men has been shown in previous studies. This is an important finding. Unfortunately, we did not have data available to delve deeper into why these disparities might be present."
The study was limited in its reliance on self-reported data, which may lead to misclassification of diabetes type and age at diabetes diagnosis. Although no information was collected on diagnostic measures, the authors noted that the definition of type 1 diabetes used in the study has been externally validated in other studies. The analysis may also underestimate the proportion of Type 1 diabetes diagnoses in childhood because all participants were at least 18 years old at the time of the survey.
Still, Selvin and colleagues concluded that there remains a need to improve diagnostic accuracy in adult-onset T1D. "Our findings are consistent with American Diabetes Association guidelines that recommend follow-up with autoantibody testing when there is clinical suspicion of type 1 diabetes," Selvin said. "Our results also suggest that more autoantibody testing may be necessary in general practice in adults to help distinguish type 1 and type 2 diabetes."
