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word count: 250 excluding headingsMain text word count: 2,564 including Table and Figure legends Tables and Figures: Tables (2) Methods Twenty-three population-based registers recorded date of diagnosis for new cases of type 1 diabetes among children under 15 years. Tests for seasonal variation in monthly counts aggregated over the 20 year period were conducted. Time series regression was used to investigate if sunshine hour and average temperature data were predictive of the 240 monthly diagnosis counts after taking account of seasonality and long term trends.Results Significant sinusoidal pattern was evident in all but two small centres with peaks in December to February and relative amplitudes ranging from 11% to 39% (median 18%). However, most centres showed significant departures from a sinusoidal pattern. Pooling results over centres, there was significant seasonal variation in each age-group at diagnosis, with least seasonal variation in those under 5 years. Boys showed greater seasonal variation than girls, particularly those aged 10-14 years. There were no differences in seasonal pattern between four five-year sub-periods. Departures from the sinusoidal trend in monthly diagnoses in the period were significantly associated with deviations from the norm in average temperature (0.8% reduction in diagnoses per 1 C excess) but not with sunshine hours.Conclusions/interpretation Seasonality was consistently apparent throughout the period in all age-groups and both sexes, but girls and the under 5s showed less marked variation. Neither sunshine hour nor average temperature data contributed in any substantial way to explaining departures from the sinusoidal pattern.

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Elevated proinsulin levels have been observed in healthy first degree relatives of Type 1 (insulin-dependent) diabetic patients. This elevation could reflect a sequele after a previous attack on the beta-cells not necessarily leading to diabetes, or represent a family trait related to the development of diabetes. When cord plasma levels of proinsulin, insulin and C-peptide from 14 newborn siblings of Type 1 diabetic patients were compared with 21 newborn control siblings unrelated to diabetic subjects, no differences were observed. Neither were any differences observed between their mothers at delivery when comparing the same parameters. In cord plasma the proinsulin levels (median and range) were higher than those in plasma from 35 adult fasting women unrelated to diabetic subjects (10, 5-83 pmol/l vs 4, 2-33 pmol/l; p < 0.001) whereas the C-peptide levels (median and range) were lower (0.20, 0.11-0.56 nmol/l vs 0.37, 0.21-0.69 nmol/l; p < 0.001). No differences in insulin levels using a highly specific insulin assay were observed. The results suggest that newborn children have high proinsulin and low C-peptide levels unrelated to heredity of diabetes and that the previously described elevated proinsulin level observed in older first degree relatives of diabetic subjects occurs later in life.

The prevalence and incidence of bacteriuria in 304 girls and 337 boys with type I diabetes was studied by screening for bacteriuria at their regular outpatient controls. In 90 girls and 108 boys a urine specimen was sampled every third month during a year. The prevalence of bacteriuria was 3/304 in girls and 0/337 in boys. During the one year follow-up one of the 90 girls had pyelonephritis and two cystitis while none of the boys had bacteriuria. It is concluded that the rate of urinary tract infection in young diabetic persons does not differ from that present in healthy young people.