Increased proinsulin levels as an early indicator of B-cell dysfunction in non-diabetic twins of type 1 (insulin-dependent) diabetic patients.
Glucose tolerance and insulin secretion were studied in two groups of non-diabetic identical twins of recently-diagnosed Type 1 (insulin-dependent) diabetic patients: (1) a group of 5 twins with islet cell antibodies, and (2) a group of 6 twins without. Despite similar fasting glucose, insulin and C-peptide concentrations both groups of twins had significantly higher fasting proinsulin concentrations than the control group (p less than 0.05). The twins with complement-fixing islet cell antibodies had reduced glucose tolerance and clearance, whilst the twins without islet cell antibodies did not. Neither group of twins showed any abnormality in insulin, C-peptide or proinsulin response to oral or intravenous glucose. We conclude that increased fasting proinsulin levels precede abnormalities of insulin secretion, and are an early indication of minor B-cell damage in these twins irrespective of their risk of developing diabetes.
Heaton
D A
DA
Department of Medicine, King's College Hospital, London, UK.
Millward
B A
BA
Gray
I P
IP
Tun
Y
Y
Hales
C N
CN
Pyke
D A
DA
Leslie
R D
RD
D001786:Blood Glucose / Q000032:analysis; D002096:C-Peptide / Q000097:blood; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000175:diagnosis / Q000235:genetics*; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood; D007515:Islets of Langerhans / Q000503:physiopathology*; D011379:Prognosis; D011384:Proinsulin / Q000097:blood*; D012016:Reference Values; D012307:Risk Factors; D014427:Twins; D014430:Twins, Monozygotic
D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin; D011384:Proinsulin