A clinically orientated approach increases the efficiency of screening for latent autoimmune diabetes in adults (LADA) in a large clinic-based cohort of patients with diabetes onset over 50 years.
OBJECTIVE
To assess if a clinically orientated approach improves screening for latent autoimmune diabetes in adults (LADA) in patients developing diabetes over age 50.


METHODS
From a clinic-based cohort of 3327 patients with Type 2 DM diagnosed over age 50 we recruited those with at least one feature suggestive of insulin deficiency: (i) fasting blood glucose > or = 15 mmol/l and/or HbA(1c) > or = 10% in spite of adequate compliance to diet and treatment; (ii) decreasing body weight > or = 10% in the previous 3 months in spite of constant diet; (iii) BMI < 25 mg/kg(2). A control group of 240 patients not presenting any of the previous criteria was randomly selected from the out-patient clinic.


RESULTS
We identified 220 (6.6%) patients, of whom 70 were positive for glutamic acid decarboxylase antibodies (GADA) and/or islet cell antibodies (ICA), giving a prevalence of LADA of 31.8% (95% CI 25.7-38.4). In contrast, no patient randomly selected from the remaining cohort had marker positivities. With respect to patients negative for both ICA and GADA, those who were positive had lower C-peptide values (0.53 +/- 0.51 vs. 0.88 +/- 0.42 nmol/l, P < 0.001); the lowest levels were found in patients in whom both antibodies were positive. In linear regression analysis, variables independently associated with fasting C-peptide were GADA (beta = -0.25, P < 0.001), ICA (beta = -0.15, P = 0.04), BMI (beta = 0.03, P < 0.001) and duration of diabetes (beta = -0.02, P < 0.001).


CONCLUSIONS
This study shows that: (i) a clinically orientated approach increases the efficiency of a screening programme for LADA, so that one in three screened patients are classified correctly; (ii) ICA and GADA positivity were negatively associated with residual beta-cell function, independent of BMI and duration of the disease; (iii) positivity for both ICA and GADA identifies patients with the lowest residual beta-cell function.
Monge
L
L
Diabetes Unit, Azienda Ospedaliera S. Giovanni Battista, Corsa Bramante 88-90, 10126 Turin, Italy. amd-to.monge@alma.it
Bruno
G
G
Pinach
S
S
Grassi
G
G
Maghenzani
G
G
Dani
F
F
Pagano
G
G
D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D001323:Autoantibodies / Q000032:analysis; D015415:Biomarkers / Q000032:analysis; D015331:Cohort Studies; D003922:Diabetes Mellitus, Type 1 / Q000175:diagnosis* / Q000503:physiopathology; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis* / Q000503:physiopathology; D003937:Diagnosis, Differential; D005260:Female; D005968:Glutamate Decarboxylase / Q000276:immunology; D006801:Humans; D007515:Islets of Langerhans / Q000503:physiopathology; D008297:Male; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged
D001323:Autoantibodies; D015415:Biomarkers; C024211:islet cell antibody; D005968:Glutamate Decarboxylase