So you think type 1 diabetes is simple – an autoimmune disease that usually starts in the first two decades of life and causes complete inability to produce insulin? Two new studies challenge the familiar paradigm. One is outlined below the other can be found in the references at the end.
Research Paper Title
Most People With Long-Duration Type 1 Diabetes in a Large Population-Based Study Are Insulin Microsecretors.
Small studies using ultra-sensitive C-peptide assays suggest endogenous insulin secretion is frequently detectable in patients with long-standing type 1 diabetes (T1D), but these studies do not use representative samples. We aimed to use the stimulated urine C-peptide-to-creatinine ratio (UCPCR) to assess C-peptide levels in a large cross-sectional, population-based study of patients with T1D.
The researchers recruited 924 patients from primary and secondary care in two UK centres who had a clinical diagnosis of T1D, were under 30 years of age when they received a diagnosis, and had a diabetes duration of >5 years. The median age at diagnosis was 11 years (interquartile range 6–17 years), and the duration of diabetes was 19 years (11–27 years). All provided a home postmeal UCPCR, which was measured using a Roche electrochemiluminescence assay.
Eighty percent of patients (740 of 924 patients) had detectable endogenous C-peptide levels (UCPCR >0.001 nmol/mmol). Most patients (52%, 483 of 924 patients) had historically very low undetectable levels (UCPCR 0.0013–0.03 nmol/mmol); 8% of patients (70 of 924 patients) had a UCPCR ≥0.2 nmol/mmol, equivalent to serum levels associated with reduced complications and hypoglycemia. Absolute UCPCR levels fell with duration of disease. Age at diagnosis and duration of disease were independent predictors of C-peptide level in multivariate modeling.
This population-based study shows that the majority of long-duration T1D patients have detectable urine C-peptide levels. While the majority of patients are insulin microsecretors, some maintain clinically relevant endogenous insulin secretion for many years after the diagnosis of diabetes. Understanding this may lead to a better understanding of pathogenesis in T1D and open new possibilities for treatment.
Published online before print December 17, 2014, doi: 10.2337/dc14-0871
Diabetes Care December 17, 2014.
Archive of Disease in Childhood 2014, doi:10.1136/archdischild-2014-306542.