title: Prevalence of detectable C-Peptide according to age at diagnosis and duration of type 1 diabetes.
abstract: OBJECTIVE
  It is generally accepted that complete β-cell destruction eventually occurs in individuals with type 1 diabetes, which has implications for treatment approaches and insurance coverage. The frequency of residual insulin secretion in a large cohort of individuals at varying ages of diagnosis and type 1 diabetes duration is unknown.
  
  
  METHODS
  The frequency of residual insulin secretion was determined by measurement of nonfasting serum C-peptide concentration in 919 individuals with type 1 diabetes according to prespecified groups based on age at diagnosis and duration of disease (from 3 to 81 years' duration). Stimulated C-peptide was measured in those with detectable nonfasting values and a group of those with undetectable values as control.
  
  
  RESULTS
  The overall frequency of detectable nonfasting C-peptide was 29%, decreasing with time from diagnosis regardless of age at diagnosis. In all duration groups, the frequency of C-peptide was higher with diagnosis age >18 years compared with ≤18 years. Nineteen percent of those with undetectable nonfasting C-peptide were C-peptide positive upon stimulation testing.
  
  
  CONCLUSIONS
  The American Diabetes Association's definition of type 1 diabetes as "usually leading to absolute insulin deficiency" results in clinicians often considering the presence of residual insulin secretion as unexpected in this population. However, our data suggest that residual secretion is present in almost one out of three individuals 3 or more years from type 1 diabetes diagnosis. The frequency of residual C-peptide decreases with time from diagnosis regardless of age at diagnosis, yet at all durations of disease, diagnosis during adulthood is associated with greater frequency and higher values of C-peptide.
authors.affiliation: Benaroya Research Institute, Seattle, WA t1dstats@jaeb.org.
authors.forename: Asa K
authors.initials: AK
authors.lastname: Davis
authors.affiliation: Jaeb Center for Health Research, Tampa, FL.
authors.forename: Stephanie N
authors.initials: SN
authors.lastname: DuBose
authors.affiliation: University of Florida, Gainesville, FL.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Haller
authors.affiliation: Jaeb Center for Health Research, Tampa, FL.
authors.forename: Kellee M
authors.initials: KM
authors.lastname: Miller
authors.affiliation: Indiana University School of Medicine, Indianapolis, IN.
authors.forename: Linda A
authors.initials: LA
authors.lastname: DiMeglio
authors.affiliation: School of Medicine and Biomedical Sciences at the University at Buffalo, The State University of New York, Buffalo, NY.
authors.forename: Kathleen E
authors.initials: KE
authors.lastname: Bethin
authors.affiliation: Naomi Berrie Diabetes Center at Columbia University, New York, NY.
authors.forename: Robin S
authors.initials: RS
authors.lastname: Goland
authors.affiliation: Naomi Berrie Diabetes Center at Columbia University, New York, NY.
authors.forename: Ellen M
authors.initials: EM
authors.lastname: Greenberg
authors.affiliation: Rocky Mountain Diabetes and Osteoporosis Center, Idaho Falls, ID.
authors.forename: David R
authors.initials: DR
authors.lastname: Liljenquist
authors.affiliation: Harold Schnitzer Diabetes Health Center, Portland, OR.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Ahmann
authors.affiliation: Northwest Lipid Metabolism and Diabetes Research Laboratories, Seattle, WA.
authors.forename: Santica M
authors.initials: SM
authors.lastname: Marcovina
authors.affiliation: Keck School of Medicine of the University of Southern California, Los Angeles, CA.
authors.forename: Anne L
authors.initials: AL
authors.lastname: Peters
authors.affiliation: Jaeb Center for Health Research, Tampa, FL.
authors.forename: Roy W
authors.initials: RW
authors.lastname: Beck
authors.affiliation: Benaroya Research Institute, Seattle, WA.
authors.forename: Carla J
authors.initials: CJ
authors.lastname: Greenbaum
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002096:C-Peptide / Q000097:blood* / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D055815:Young Adult
chemical_list: D002096:C-Peptide; D007328:Insulin