It has now been 15 months since the U.S. Preventive Services Task Force (USPSTF) last met. In the interim, several members' 4-year terms expired, and HHS Secretary RFK Jr. fired the two remaining Vice Chairs, leaving the USPSTF leaderless and without a voting quorum. Although much of the work of the Task Force occurs on conference calls in between scheduled meetings, no new recommendations can be debated or finalized in the current situation. Even if new members with appropriate qualifications are eventually appointed, the future of the USPSTF remains uncertain. So when a new study suggests that a screening test could be beneficial, clinicians and medical groups can only make their best guess about what the USPSTF might recommend based on the evidence.
Unlike prediabetes and type 2 diabetes, the USPSTF has never evaluated screening for type 1 diabetes in the general population. There are two major rationales for screening. First, a large percentage of persons are not diagnosed until they develop symptoms of diabetic ketoacidosis (DKA), a life-threatening situation that invariably requires hospitalization and frequently a stay in the intensive care unit. Second, a therapy exists that delays the onset of the disease in children determined to be high risk. Although the Centers for Disease Control and Prevention and expert groups recommend screening relatives of persons with type 1 diabetes with autoantibody tests, the vast majority of persons who are diagnosed have no family history.
The ideal type of study to establish the benefits and harms of screening for type 1 diabetes would be a randomized trial where participants were randomly assigned to screening or control groups and followed for important clinical outcomes such as DKA, diabetes complications, and mortality. But type 1 diabetes is not nearly as common as type 2, and thousands of participants would need to be followed for years to detect a statistically significant difference in outcomes. This large-scale study would require an investment of money and resources that no private or public funder has thus far been willing to support.
Instead, individual screening programs have been implemented in various locations around the world. Some are focusing on screening relatives of persons with type 1 diabetes, while others are screening the general population in primary care settings. One of the latter programs in Germany was established in 2015 and recently reported 10-year outcomes in a paper in JAMA. Out of more than 220,000 children screened, 590 (0.3%) had autoantibodies but no clinical symptoms. After 5 years, 36% of those with positive screens had progressed to clinical type 1 diabetes, representing 81% of all children who ultimately received this diagnosis. Of note, the progression rate was similar in children with and without a first-degree relative with type 1 diabetes.
Without a comparison group, we don't know how these children would have fared in the absence of screening. Did some of them avoid a traumatic hospitalization for DKA or receive therapy that gave them a few more years without clinical symptoms? Conversely, did they or their loved ones experience negative psychological effects from being a given an early diagnosis, particularly the 64% who had not progressed to clinical diabetes after 5 years? The researchers don't say. My guess is that the USPSTF would have deemed this study to be insufficient evidence to assess the balance of benefits and harms of screening all children for type 1 diabetes. Absent a formal evidence assessment, though, I suspect that many well-intentioned experts will push prematurely for screening to take place anyway - which is why the Task Force needs to be restored and reconvened without further delay.