In 52 obese children selected for elevated proinsulin levels and/or impaired glucose tolerance, we found eight known variants and two novel heterozygous variants (c.1095 + 1G > A and p.S24C) by sequencing the <i>PCSK1</i> gene.
In animal models for type 2 diabetes the contents of preproinsulin mRNA are lowered, which might suggest that an impaired metabolism of preproinsulin mRNA contributes to the development of glucose intolerance and diabetes.
In adults with impaired glucose tolerance (IGT) and obesity (OB), an elevated proinsulin (PI) is predictive of type 2 diabetes mellitus (DM) and precedes the diagnosis by 5-20 yr.
Oral glucose tolerance tests on subjects with the presenilin 2 Met239Val mutation unaffected by early onset familial Alzheimer's disease (mean age 35 years) and on their first-degree relatives without the mutation demonstrated no evidence of glucose intolerance or increased proinsulin secretion.
We determined GAD and islet cell (ICA512) autoantibodies from 215 NIDDM individuals and from 14 individuals with impaired glucose tolerance (IGT) of 68 families, including 1 family with maturity-onset diabetes of the young (MODY) and 3 families ascertained specifically for a mixture of NIDDM and IDDM.
Based on the recent demonstration of elevated serum proinsulin levels in cystic fibrosis patients with impaired glucose tolerance, it was hypothesized that proinsulin could be an indicator of altered beta-cell function.
Recent epidemiologic studies of the determinants and natural history of IDDM using HLA typing and detecting islet cell antibodies have shown that HLA-identical siblings of probands with IDDM are at extremely high risk of developing IDDM, and that islet cell antibodies and glucose intolerance usually appear long before clinical manifestations.