IA-2A与GADA检测对1型糖尿病的诊断价值

Diagnostic value of IA-2A and GADA assays in type 1 diabetes

目的 了解蛋白酪氨酸磷酸酶抗体 (IA 2A )与谷氨酸脱羧酶抗体 (GADA)在 1型糖尿病(DM )中的检出率及其诊断价值。方法 采用放射配体法检测 114例 1型DM患者及 188名正常对照者IA 2A与GADA水平 ,并以放免法检测 1型DM患者空腹C肽 (FCP)、甲状腺球蛋白抗体 (TGAb)与甲状腺过氧化物酶抗体 (TPOAb)水平。结果 (1) 1型DM患者中GADA、IA 2A检出率分别为 49.1% (5 6/114 )和 2 4.6% (2 8/114 ) ,高于正常对照 1.1%与 0 .6% (均P <0 .0 1)。 15岁以下、病程≤ 0 .5年的 1型DM患者GADA、IA 2A检出率分别为 66.7% (8/12 )和 5 8.3 % (7/12 ) ,与白种人 (5 6.0 %～ 82 .0 %与 5 6.4%～74.4% )比较 ,GADA差异无显著性 ;而IA 2A仅低于检出率最高的国家芬兰 (85 .7% ,P <0 .0 1) ;(2 ) 15岁以下与 15岁以上 1型DM组GADA阳性率分别为 61.8% (2 1/3 4)和 43 .8% (3 5 /80 ,P >0 .0 5 ) ;而IA 2A阳性率分别为 41.2 % (14 /3 4)和 17.5 % (14 /80 ,P <0 .0 1)。病程 1年以内与病程 1年以上 1型DM患者GADA阳性率分别为 5 6.4% (3 1/5 5 )与 42 .4% (2 5 /5 9,P >0 .0 5 ) ;而IA 2A阳性率分别为 3 4.5 % (19/5 5 )对 15 .2 % (9/5 9,P <0 .0 5 ) ;(3 ) 1型DM中GADA和IA 2A阳性患者与GADA和IA 2A阴性患者比较 ,FCP水平较?

Objective To investigate the positive rates of protein tyrosine phosphatase antibody (IA-2A) and glutamic acid decarboxylase antibody (GADA) and their diagnostic value in type 1 diabetes mellitus (DM). Methods IA-2A and GADA were determined in 114 patients with type 1 diabetes and 188 healthy controls by radioligand assay(RLA). Fasting C peptide (FCP), thyroglobulin antibody (TGAb) and thyroid peroxidase antibody (TPOAb) were measured in type 1 DM patients by radioimmune assay. Results (1) Among 114 type 1 DM cases, 49.1%(56/114) of them had positive GADA, 24.6%(28/114) positive IA-2A, while the positive rates in 188 healthy controls were 1.1% and 0.6%, respectively. Higher levels of these two antibodies were seen in type 1 DM patients compared with healthy controls (all P<0.01).ThepositiveratesofGADA and IA-2A were 66.7%(8/12), 58.3%(7/12) in patients aged under 15 years with duration of illness less than half a year, being comparable with that of newly diagnosed Caucasian type 1 DM cases under 15 years of age (56.0%-82.0% and 56.4%-74.4%,respectively). The difference of GADA was not significant, but that of IA-2A was significantly lower than the highest one in Finnish type 1 DM patients (85.7%, P<0.01). (2) The difference of positive rate of GADA was not significant (GADA 61.8% vs 43.8%) between patients under and over 15 years of age, but it was significant for that of IA-2A (41.2% vs 17.5%, P<0.01). The difference of positive rate for GADA in patients with duration of illness more and less than 1 year was not significant (56.4% vs 42.4%), while that for IA-2A was significant (34.5% vs 15.2%, P<0.05). (3) Fasting C-peptide level in GADA and IA-2A positive diabetics was lower than that of antibody-negative ones (both P<0.05). (4) The positive rates of either TGAb or TPOAb in patients with single GADA positivity (38.5%) was higher than that of single IA-2A positivity (0%, P<0.05). (5) The combined positive rates of GADA and IA-2A among 114 type 1 DM patients was 58.8%, and was 69.1% in 55 type 1 DM patients with duration of illness less than 1 year, being higher than the positive rate of single IA-2A antibody assay (P<0.05). Conclusions (1) The positive rates of GADA and IA-2A in Chinese newly diagnosed childhood-onset type 1 DM are similar to those in European and American whites. The positive rate of IA-2A is closely associated with the age of onset and duration of illness, while GADA is not. (2) The positive GADA or IA-2A may predict poor islet β-cell function. As islet autoantibodies, the specificity of IA-2A appears to be superior to GADA. (3) The combined determination of GADA and IA-2A can increase diagnostic sensitivity for autoimmune type 1 DM.