Age at onset do not influence long-term glycemic control in children with type 1 diabetes mellitus

Background. Studies indicate that younger patients show a significantly lower C-peptide secretion and a more difficult metabolic control at onset and during the first years after the diagnosis of type 1 diabetes mellitus. It is not so clear whether these differences persist also after a higher number of years of disease duration and whether they may justify the different results obtained by the new therapeutic regimens in the various period of life. Objective. To compare, at 1, 3 and 5 years of disease, metabolic control, C-peptide levels and insulin-dose requirement in two groups of children, who developed type 1 diabetes between 1994 and 2002: Group 1 (n. 42) with onset before the age of 5 yrs (n.22 < 3 yrs) and Group 2 (n.38) with onset after the age of 10 years. N. 73 have completed a 3 year and n. 55 a 5 year follow-up. All patients of Group 2 were pubertal at the end of follow-up. Results. At 1 and 3, but not 5 years of disease, the percentage of cases with detectable levels of C-peptide and mean C-peptide values were significantly higher in Group 1 than in Group 2. C-peptide levels correlated significantly with age at onset at all times considered. On the contrary, the age at onset correlated with HbA1c mean levels and insulin-dose requirement only after 1 yr, and mean annual HbA1c values were not significantly different in the two groups at any time of follow-up. These HbA1c values were again similar, even if we considered only the cases, in the two groups, with undetectable Cpeptide. Conclusions: Age at onset and a good preserved residual beta-cell function are unable, years after the onset of the disease, to influence the long-term glycemic control. It should be remembered, however, that this comparison is not wholly homogeneous, since, obviously, only Group 2 is influenced by puberty, another variable with a strong effect on metabolic control.