HLA-DQB1 genotypes, islet antibodies and beta cell function in the classification of recent-onset diabetes among young adults in the nationwide Diabetes Incidence Study in Sweden

Common variants in the TCF7L2 gene help to differentiate autoimmune from non-autoimmune diabetes in young (15–34 years) but not in middle-aged (40–59 years) diabetic patients

“…In 1,642 of 1,824 diabetic patients (age at onset 15-34 years) from the Diabetes Incidence Study in Sweden (DISS) [3], islet antibodies (ICA, GADA, IA-2A) at diagnosis were measured. Fasting plasma C-peptide was measured at 3 to 6 months after diagnosis in 1,353 participants and HLA-DQB1, INS VNTR, PTPN22 and the TCF7L2 single nucleotide polymorphisms (SNPs), rs7903146 and rs10885406 were genotyped in 1,564 of these Swedish diabetic patients.…”

“…An RIA was used to determine fasting plasma C-peptide (Peninsula Laboratories, Belmont, CA, USA) in young (age 15-34 years) [3] and middle-aged (age 40-59 years) diabetic patients [26]. The reference range for healthy participants after 12 h fasting was 0.25 to 0.75 nmol/l.…”

“…Common allelic variants at the HLA class II loci account for the major genetic risk in children and young adults [1][2][3]. Islet cell antibodies (ICA), glutamic acid decarboxylase antibodies (GADA), IA-2-protein tyrosine phosphatase-like protein antibodies (IA-2A) and insulin autoantibodies are established autoimmune markers of type 1 diabetes, but it is not clear whether they identify the same disease in young and adult diabetic patients [4][5][6].…”

“…Also, to date, diagnosis of type 2 diabetes has been by exclusion, with patients not presenting with genetic and autoimmune markers of type 1 diabetes being considered to have type 2 diabetes [3,11,16,17]. Apart from HLA, no other genetic markers have been used to distinguish type 1 and type 2 diabetes in young and middle-aged adults.…”

Long-term detrimental consequences of the onset of type 1 diabetes on annual earnings—evidence from annual registry data in 1990–2005

“…Since 1992 the diagnostic criteria used [18] are those recommended by the American Diabetes Association expert group [22], in clinical settings corresponding to those of WHO [23]. The clinical classification has been shown to correspond well to the presence of islet cell antibodies and C-peptide concentrations [24,25]. For the period 1983-2005, 73% of individuals were registered as having type 1 diabetes, 17% as having type 2 diabetes and 10% were unclassifiable at the time of diagnosis.…”