The trajectory of IGF-1 across age and duration of type 1 diabetes.
BACKGROUND
Individuals with type 1 diabetes may have low IGF-1, related to insulinopenia and insulin resistance. There are few longitudinal studies of IGF-1 levels to establish its pattern in type 1 diabetes with duration and age, and to examine whether IGF-1 tracks within individuals over time. We examine age and duration trends, and the relationship of IGF-1 to gender, glycaemic control, insulin level and other factors.


METHODS
Participants in the Wisconsin Diabetes Registry Study, an incident cohort study of type 1 diabetes diagnosed May 1987-April 1992, were followed for up to 18 years with IGF-1 samples up to age 45 for women and age 37 for men.


RESULTS
IGF-1 is lower with type 1 diabetes than in normative samples. Although, the pattern across age resembles that in normative samples with a peak in adolescence and slow decline after age 20, the adolescent peak is delayed for women with type 1 diabetes. There was low to moderate tracking of IGF-1 within an individual. Higher insulin dose was associated with higher IGF-1 as was puberty, and female gender. Adjusted for these factors, IGF-1 declined rapidly across early diabetes duration. Lower HbA1c was most strongly related to higher IGF-1 at Tanner stages 1 and 2.


CONCLUSIONS
IGF-1 is low in type 1 diabetes, with a delayed adolescent peak in women and is especially influenced by glycaemic control in early and pre-adolescence. High variability within an individual is likely a challenge in investigating associations between IGF-1 and long-term outcomes, and may explain contradictory findings.
Department of Population Health Sciences, University of Wisconsin, Madison, WI, United States; Department of Biostatistics and Medical Informatics, University of Wisconsin, Madison, WI, United States.
Mari
M
Palta
Tamara J
TJ
LeCaire
Mona
M
Sadek-Badawi
Victor M
VM
Herrera
Kirstie K
KK
Danielson
D000293:Adolescent; D000328:Adult; D000375:Aging; D002648:Child; D015331:Cohort Studies; D048909:Diabetes Complications / Q000453:epidemiology / Q000517:prevention & control*; D003922:Diabetes Mellitus, Type 1 / Q000150:complications / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D018450:Disease Progression; D015536:Down-Regulation; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000097:blood / Q000627:therapeutic use; D007328:Insulin / Q000097:blood / Q000627:therapeutic use*; D007333:Insulin Resistance; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D008137:Longitudinal Studies; D008297:Male; D011446:Prospective Studies; D012042:Registries; D012307:Risk Factors; D012727:Sex Characteristics; D015854:Up-Regulation / Q000187:drug effects*; D014922:Wisconsin / Q000453:epidemiology; D055815:Young Adult
D007004:Hypoglycemic Agents; C583557:IGF1 protein, human; D007328:Insulin; D007334:Insulin-Like Growth Factor I
IGF-1; predictors; tracking; trajectory; type 1 diabetes; variance