The Association Between IGF-I and Insulin Resistance

A general population study in Danish adults

Friedrich, Nele PHD
Thuesen, Betina PHD
Jørgensen, Torben MD
Juul, Anders MD
Spielhagen, Christin MD
Wallaschofksi, Henri MD
Linneberg, Allan MD

¹Institute of Clinical Chemistry and Laboratory Medicine, University Medicine Greifswald, Greifswald, Germany
²Research Centre for Prevention and Health, the Capital Region of Denmark, Denmark
³Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
⁴Department of Growth and Reproduction, Rigshospitalet, Copenhagen, Denmark

Corresponding author: Nele Friedrich, [email protected].

Received September 21, 2011

Accepted December 23, 2011

Diabetes Care 35(4):p 768-773, April 2012. | DOI: 10.2337/dc11-1833

OBJECTIVE

IGF-I has an almost 50% amino acid sequence homology with insulin and elicits nearly the same hypoglycemic response. Studies showed that low and high IGF-I levels are related to impaired glucose tolerance and to a higher risk of type 2 diabetes. The aim of the current study was to evaluate the association between IGF-I level and insulin resistance in a Danish general population.

RESEARCH DESIGN AND METHODS

Included were 3,354 adults, aged 19–72 years, from the cross-sectional Health2006 study. The homeostasis model assessment of insulin resistance (HOMA-IR) was used as the index to estimate insulin resistance. Serum IGF-I levels were determined by an immunoassay and grouped into quintiles (Q1–Q5). Linear or multinomial logistic regression analyses were performed.

RESULTS

In the study population, 520 subjects (15.5%) had increased HOMA-IR values above 2.5. After adjustment for age, sex, physical activity, and waist-to-height ratio, a U-shaped association between IGF-I and HOMA-IR was found. Low IGF-I (Q1: odds ratio [OR] 1.65 [95% CI 1.16–2.34], P < 0.01) as well as high IGF-I (Q5: 1.96 [1.38–2.79], P < 0.01) levels were related to a higher odds of increased HOMA-IR values compared with subjects with intermediate (Q3) IGF-I levels. These associations remained statistically significant after the exclusion of subjects with type 2 diabetes and by using the updated computer HOMA2-IR model.

CONCLUSIONS

Low- and high-normal IGF-I levels are both related to insulin resistance. The biological mechanism of this complex phenomenon has to be elucidated in more detail for future risk stratification.