medwireNews: Children with familial type 1 diabetes have different characteristics to those with sporadic diabetes at presentation, but longer-term outcomes are similar, say researchers.
“Familial type 1 diabetes in this study was characterized by younger age at onset and higher prevalence of associated autoimmune disease in comparison with sporadic type 1 diabetes,” report Beate Karges (RWTH Aachen University, Germany) and study co-authors.
The 3765 children (younger than 20 years) with familial diabetes, identified in the DPV registry, were a median age of 7.9 years at diagnosis, compared with 9.7 years for the 53,606 children with sporadic type 1 diabetes.
Rates of autoimmune disease were 16.7% versus 13.6% among children with familial versus sporadic diabetes. The most common autoimmune disease was thyroid disease (11.6 vs 10.0%), followed by celiac disease (6.2 vs 4.2%) and Addison disease (0.1 vs 0.05%).
However, children with familial diabetes had lower glucose levels at presentation than those with sporadic diabetes, and less often presented with diabetic ketoacidosis.
Specifically, average glucose levels were 390 versus 417 mg/dL (21.6 vs 23.1 mmol/L), median glycated hemoglobin (HbA1c) levels were 9.7% versus 11.1% (83 vs 98 mmol/mol), and ketoacidosis rates were 11.9% versus 20.4%.
“It is likely that higher disease awareness in [families with pre-existing type 1 diabetes] contributes to timely recognition and diagnosis and, hence, earlier initiation of therapy in the second family member,” the researchers write in Diabetes Care.
Of note, the 948 children who had familial type 1 diabetes but were the first in their families to develop it had the youngest age at onset (median 6.5 years), the highest ketoacidosis rate (24.1%), and the highest median blood glucose level (442 mg/dL; 24.5 mmol/L).
These findings “point to more aggressive autoimmunity in familial diabetes,” say Karges and team.
But over the longer term children with familial and sporadic type 1 diabetes had a similar disease course. Median HbA1c levels during the first year after diagnosis were 7.1% and 7.2% (54 and 55 mmol/mol), respectively, and the median daily insulin doses were 0.5 and 0.6 IU/kg.
Children with familial diabetes, however, had a slightly higher rate of partial remission than those with sporadic diabetes, at 64.1% versus 61.2%, driven by higher rates in those who had a pre-existing family member with diabetes (66.5%).
The researchers suggest this may be due to early disease recognition allowing early insulin treatment, promoting partial beta-cell recovery.
“Familial expertise with type 1 diabetes therapy may further explain better glycemic control in the first year, higher acceptance of insulin pump use during initial treatment, and fewer events of severe hypoglycemia in the relative-first group,” they add.
In all, 34.1% of children with pre-existing type 1 diabetes in the family were using an insulin pump in the first year, compared with 18.3% of those with sporadic diabetes.
Nevertheless, the team concludes “that familial and sporadic type 1 diabetes are overall similar,” meaning the two subgroups do not need to be distinguished in clinical trials of type 1 diabetes prevention, which largely recruit people with familial diabetes, despite sporadic type 1 diabetes being much more common.
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