title: Insulin resistance and fasting plasma glucose in first degree relatives of patients with type 1 diabetes.
abstract: BACKGROUND
  We analyzed the relationship between fasting plasma glucose (FPG), the presence of autoantibodies, first phase of insulin secretion and insulin resistance in the first degree relatives of patients with type 1 diabetes.
  
  
  METHODS
  The group studied consisted of 90 healthy relatives, divided into two groups: "high-normal" FPG group (≥88mg/dl) and "low-normal" FPG group (<88/mg/dl). All subjects underwent an intravenous glucose tolerance test, and the 1st phase insulin response (FPIR) and FPIR-to-HOMA-IR-ratio were calculated. Additionally, islet autoantibodies (GADA, IAA and IA-2A) were determined by radioimmunoassays.
  
  
  RESULTS
  The subjects with "high-normal" FPG were older (p=0.0009), had higher BMI (p<0.0001) and lower HOMA%B (p=0.0004), FPIR (p=0.006) and FPIR-to-HOMA-IR-ratio (p=0.004) in comparison with the "low-normal" FPG group. Autoantibodies were present in 40.9% and in 21.7% of the subjects with "high-normal" and "low-normal" FPG, respectively. In the "high-normal" FPG group, FPG correlated positively with GADA (r=0.31, p=0.04), and HOMA-IR (r=0.19, p=0.02), and negatively with HOMA%B (r=-0.36, p=0.001), whereas FPIR correlated positively with HOMA%B (r=0.55, p=0.0001) and BMI (r=0.30, p=0.04). After an adjustment for BMI, the difference in FPIR between the "high-normal" and "low-normal" FPG groups remained significant (p=0.025), whereas the difference in FPIR-to-HOMA-IR-ratio became insignificant.
  
  
  CONCLUSIONS
  Our results suggest that taking into account the impact of age and BMI on insulin sensitivity, it would be expected that the relatives of patients with type 1 diabetes with "high-normal" glucose levels would become gradually unable to compensate for increasing insulin resistance.
authors.affiliation: Department of Endocrinology, Diabetology and Internal Medicine, Medical University of Bialystok, Poland. Electronic address: katarzynasiewko@go2.pl.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Siewko
authors.forename: Anna
authors.initials: A
authors.lastname: Popławska-Kita
authors.forename: Beata
authors.initials: B
authors.lastname: Telejko
authors.forename: Rafał
authors.initials: R
authors.lastname: Maciulewski
authors.forename: Anna
authors.initials: A
authors.lastname: Zielińska
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Nikołajuk
authors.forename: Maria
authors.initials: M
authors.lastname: Górska
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Szelachowska
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood; D001786:Blood Glucose / Q000032:analysis*; D003922:Diabetes Mellitus, Type 1; D005190:Family; D005215:Fasting / Q000097:blood*; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D055815:Young Adult
chemical_list: D001323:Autoantibodies; D001786:Blood Glucose; D007328:Insulin
keywords: First phase insulin secretion; GADA; IAA; Type 1 diabetes