Defining the Decline in Endogenous Insulin Secretion in Type 1 Diabetes Diagnosed After 30 Years of Age.
Defining the Decline in Endogenous Insulin Secretion in Type 1 Diabetes Diagnosed After 30 Years of Age.
The study aims is to find out if people with type 1 diabetes diagnosed in later life (after
 age 30) have the same rapid loss of insulin secretion (measured using C-peptide) that occurs
 in younger adults with type 1 diabetes. The investigators will recruit 135 participants aged
 over 30 years with a clinical diagnosis of type 1 diabetes and diabetes duration ≤100 days.
 The investigators will also recruit a comparison group of 61 participants aged 18-30 with a
 clinical diagnosis of type 1 diabetes and diabetes duration ≤100 days. C-peptide will be
 measured during mixed meal tolerance tests (MMTT) performed at baseline, 6 months and a year.

 This study also aims to test a new more practical way of monitoring insulin secretion at home
 using a finger prick 'blood spot' rather than time consuming tests in a hospital.
 Finger-prick C-peptide samples will be collected after the MMTT and by the participants at
 home throughout the year.
The study aims to evaluate progression of type 1 diabetes. Primary analysis will be conducted
 on those with >=1 diabetes autoantibody positive (GAD, IA2 ZNT8). Sensitivity analysis will
 be performed by repeating all analysis defining T1D as a) double antibody positivity and b)
 single antibody positivity combined with a high genetic risk score for T1D (T1DGRS>5th
 centile of a control population).

 Further aims will be to evaluate the utility of dried blood spot testing to detect change in
 C-peptide and the utility of home test results as a marker of hypoglycaemia and glucose
 variability.
Inclusion Criteria:

 -  Adults with a clinical diagnosis of Type 1 diabetes within the previous 100 days.

 -  Aged >30 at the time of Type 1 diabetes diagnosis OR (additional early onset Type 1
 diabetes cohort) aged ≥18 and ≤30 at the time of Type 1 diabetes diagnosis.

 -  Insulin treated at the time of recruitment

 -  Able and willing to provide informed consent.

 Exclusion criteria

 -  Pregnancy

 -  Known monogenic diabetes

 -  Known secondary diabetes (diabetes considered likely due to medication, cystic
 fibrosis, pancreatitis, pancreatic cancer, pancreatic surgery, hemochromatosis or
 Cushing's syndrome).