Screening for diabetes risk
Risk based on diabetes-associated autoantibodies
Screening of relatives has led to the identification of three risk groups: relatives with a high, moderate and low risk of developing type 1 diabetes. It is however important to know that these are risks and NOT certainties.
Risk assessment is based on results of 4 blood samples, except for the high risk, which can already be determined after 1 blood sample tested.
Screening based on the search for autoantibodies directed against insulin (IAA), glutamate decarboxylase (GADA), IA-2 (IA-2A), and zinc transporter 8 (ZnT8A).
Overview of risk groups
low risk | Moderate risk | High risk | |
---|---|---|---|
Marker | no diabetes antibodies present | Presence of only 1 antibody or only IAA and GADA | Presence of IA-2A or ZnT8A plus at least one other antibody |
Prevalence | more than 90 out of 100 participants | approximately 7 out of 100 participants | 1 out of 100 participants |
Risk of diabetes within 4 years | less than 1% | 5 to 10% | more than 50% |
Proposed follow-up |
blood sample (frequency depending on genetic risk and age) | annual blood sample or intensified metabolic follow-up | participation in a prevention study when available or intensified metabolic follow-up |
Contribution of hyperglycemic clamptest
Hyperglycaemic clamps were performed in 17 non-diabetic IA-2A+ FDRs aged 14 to 33 years and in 21 matched healthy volunteers. Insulin and C-peptide responses were measured during the first (5?10 min) and second (120?150 min) release phase, and after glucagon injection (150?160 min). C-peptide levels below percentile 10 of the healthy voluteers were considered decreased.
All five FDRs with low first-phase release also had low second-phase release and developed diabetes 3?21 months later. Two of seven FDRs with normal firstphase but low second-phase release developed diabetes after 34 and 63 months, respectively. None of the five FDRs with normal C-peptide responses in all test phases has developed diabetes so far (follow-up 56 to 99 months).
These results show that the hyperglycemic clamp test contributes to risk prediction in IA-2A-positive first degree relatives.
Scheme of an hyperglycemic clamp test