Prediction of type 1 diabetes

Area of Science:

• Immunology
• Endocrinology
• Genetics

Background:

• Type 1 diabetes prediction relies on islet cell antibodies (ICA), but other markers may enhance accuracy.
• First-degree relatives of type 1 diabetic patients are at higher risk and are ideal candidates for predictive screening.

Purpose of the Study:

• To evaluate the predictive value of islet cell antibodies (ICA) and insulin autoantibodies (IAA) in relatives of type 1 diabetes patients.
• To assess the combined predictive power of ICA and IAA, and the role of HLA markers in disease progression.

Main Methods:

• Screening of 1460 first-degree relatives using ICA and IAA assays.
• Longitudinal follow-up for 5 years to identify progression to insulin-dependent diabetes mellitus (IDDM).
• HLA DR and DQ genotyping for antibody-positive relatives.

Main Results:

• 17 out of 44 antibody-positive relatives (39%) developed IDDM within 5 years.
• ICA screening showed 94% sensitivity for predicting IDDM, compared to 65% for IAA.
• Combining ICA and IAA increased the risk prediction to 67%.
• Relatives with two non-DR3/non-DR4 HLA alleles showed no risk of IDDM, regardless of antibody status.

Conclusions:

• Islet cell antibodies (ICA) are more sensitive than insulin autoantibodies (IAA) for predicting type 1 diabetes progression.
• Combined ICA and IAA screening improves prediction accuracy.
• HLA genotyping can identify antibody-positive individuals at low risk, potentially excluding them from intervention trials.