Familial clustering of insulin sensitivity

Area of Science:

• Genetics
• Metabolic Disorders
• Human Physiology

Background:

• Insulin sensitivity (SI) and insulin-independent glucose uptake (SG) are key metabolic parameters.
• Understanding the genetic basis of these traits is crucial for comprehending metabolic health and disease.

Purpose of the Study:

• To investigate familial clustering of insulin sensitivity (SI) and insulin-independent glucose uptake (SG).
• To determine if these traits are genetically determined.

Main Methods:

• Utilized a 3-hour intravenous glucose tolerance test in 183 non-diabetic individuals from 105 families.
• Estimated SI and SG using the minimal model of glucose disposal.
• Employed intraclass correlation coefficients to assess familial aggregation.

Main Results:

• Insulin sensitivity (SI) exhibited significant familial clustering (intraclass correlation = 0.26, P = 0.008).
• Insulin-independent glucose uptake (SG) did not show significant familial clustering (intraclass correlation = 0.081, P = 0.45).
• SI and SG were uncorrelated (r = -0.059, P = 0.42).
• High within-sibship variability in SI was observed in some families, suggesting a potential major gene effect.

Conclusions:

• Familial clustering of SI supports a polygenic determinant for insulin sensitivity.
• The lack of clustering for SG suggests distinct genetic or environmental influences.
• Evidence points towards a complex genetic architecture for insulin sensitivity, possibly involving major gene effects.