The pancreatic islet beta-cell autoantigen of relative molecular mass 64,000 (64K), which is a major target of autoantibodies associated with the development of insulin-dependent diabetes mellitus (IDDM) has been identified as glutamic acid decarboxylase, the biosynthesizing enzyme of the inhibitory neurotransmitter GABA (gamma-aminobutyric acid). Pancreatic beta cells and a subpopulation of central nervous system neurons express high levels of this enzyme. Autoantibodies against glutamic acid decarboxylase with a higher titre and increased epitope recognition compared with those usually associated with IDDM are found in stiff-man syndrome, a rare neurological disorder characterized by a high coincidence with IDDM.

OBJECTIVE -It is unclear whether the demands of good metabolic control or the consequences of poor control have a greater influence on quality of life (QOL) for adolescents with diabetes. This study aimed to assess these relations in a large international cohort of adolescents with diabetes and their families.RESEARCH DESIGN AND METHODS -The study involved 2,101 adolescents, aged 10 -18 years, from 21 centers in 17 countries in Europe, Japan, and North America. Clinical and demographic data were collected from March through August 1998. HbA 1c was analyzed centrally (normal range 4.4 -6.3%; mean 5.4%). Adolescent QOL was assessed by a previously developed Diabetes Quality of Life (DQOL) questionnaire for adolescents, measuring the impact of diabetes, worries about diabetes, satisfaction with life, and health perception. Parents and health professionals assessed family burden using newly constructed questionnaires.RESULTS -Mean HbA 1c was 8.7% (range 4.8 -17.4). Lower HbA 1c was associated with lower impact (P Ͻ 0.0001), fewer worries (P Ͻ 0.05), greater satisfaction (P Ͻ 0.0001), and better health perception (P Ͻ 0.0001) for adolescents. Girls showed increased worries (P Ͻ 0.01), less satisfaction, and poorer health perception (P Ͻ 0.01) earlier than boys. Parent and health professional perceptions of burden decreased with age of adolescent (P Ͻ 0.0001).Patients from ethnic minorities had poorer scores for impact (P Ͻ 0.0001), worries (P Ͻ 0.05), and health perception (P Ͻ 0.01). There was no correlation between adolescent and parent or between adolescent and professional scores.CONCLUSIONS -In a multiple regression model, lower HbA 1c was significantly associated with better adolescent-rated QOL on all four subscales and with lower perceived family burden as assessed by parents and health professionals.

These results suggest that there are substantial variations in glycaemic control among people with Type 1 diabetes between the data sources and that there is room for improvement in all populations, especially in young adults.

OBJECTIVE -To reevaluate the persistence and stability of previously observed differences between pediatric diabetes centers and to investigate the influence of demography, language communication problems, and changes in insulin regimens on metabolic outcome, hypoglycemia, and ketoacidosis. RESULTS -Mean A1C was 8.2 Ϯ 1.4%, with substantial variation between centers (mean A1C range 7.4 -9.2%; P Ͻ 0.001). There were no significant differences between centers in rates of severe hypoglycemia or diabetic ketoacidosis. Language difficulties had a significant negative impact on metabolic outcome (A1C 8.5 Ϯ 2.0% vs. 8.2 Ϯ 1.4% for those with language difficulties vs. those without, respectively; P Ͻ 0.05). After adjustement for significant confounders of age, sex, duration of diabetes, insulin regimen, insulin dose, BMI, and language difficulties, the center differences persisted, and the effect size for center was not reduced. Relative center ranking since 1998 has remained stable, with no significant change in A1C. RESEARCH DESIGN AND METHODSCONCLUSIONS -Despite many changes in diabetes management, major differences in metabolic outcome between 21 international pediatric diabetes centers persist. Different application between centers in the implementation of insulin treatment appears to be of more importance and needs further exploration.

OBJECTIVE -Twenty-one international pediatric diabetes centers from 17 countries investigated the effect of simple feedback about the grand mean HbA 1c level of all centers and the average value of each center on changes in metabolic control, rate of severe hypoglycemia, and insulin therapy over a 3-year period.RESEARCH DESIGN AND METHODS -Clinical data collection and determination of HbA 1c levels were conducted at a central location in 1995 (n ϭ 2,780, age 0 -18 years) and 1998 (n ϭ 2,101, age 11-18 years).RESULTS -Striking differences in average HbA 1c concentrations were found among centers; these differences remained after adjustment for the significant confounders of sex, age, and diabetes duration. They were apparent even in patients with short diabetes duration and remained stable 3 years later (mean adjusted HbA 1c level: 8.62 Ϯ 0.03 vs. 8.67 Ϯ 0.04 [1995 vs. 1998, respectively]). Three centers had improved significantly, four centers had deteriorated significantly in their overall adjusted HbA 1c levels, and 14 centers had not changed in glycemic control. During the observation period, there were increases in the adjusted insulin dose by 0.076 U/kg, the adjusted number of injections by 0.23 injections per day, and the adjusted BMI by 0.95 kg/m 2 . The 1995 versus 1998 difference in glycemic control for the seven centers could not be explained by prevailing insulin regimens or rates of hypoglycemia.CONCLUSIONS -This study reveals significant outcome differences among large international pediatric diabetes centers. Feedback and comparison of HbA 1c levels led to an intensification of insulin therapy in most centers, but improved glycemic control in only a few.