Type 2 Diabetes and Adiposity Induce Different Lipid Profile Disorders: A Mendelian Randomization Analysis

Area of Science:

• Genetics and Epidemiology
• Metabolic Diseases
• Cardiovascular Health

Background:

• Type 2 diabetes and obesity frequently coexist, creating challenges in determining their independent effects on hyperlipidemia.
• Reverse causation and confounding factors complicate the understanding of diabetes and obesity's impact on lipid profiles.

Purpose of the Study:

• To investigate the causal relationships between type 2 diabetes, adiposity (measured by BMI), and various lipid profiles.
• To utilize Mendelian randomization to disentangle the independent effects of diabetes and obesity on lipid levels.

Main Methods:

• Employed Mendelian randomization analyses with genetic risk scores as instrumental variables.
• Analyzed data from 9798 participants across 23 sites in East China (2014-2016).
• Assessed causal effects on total cholesterol, HDL-C, LDL-C, and triglycerides (TGs).

Main Results:

• Genetically determined type 2 diabetes showed a significant positive causal effect on total cholesterol (βIV=0.130) and LDL-C (βIV=0.125).
• A 10 kg/m² increase in genetically determined BMI had a significant negative causal effect on HDL-C (βIV=-0.409) and a positive effect on TGs (βIV=0.227).
• No significant causal effects were observed for diabetes on HDL-C or TGs, nor for BMI on LDL-C.

Conclusions:

• This Mendelian randomization study provides evidence for biologically plausible causal links between type 2 diabetes and specific lipid components.
• Adiposity, as indicated by BMI, demonstrates causal effects on HDL-C and triglycerides, independent of diabetes.
• The findings support distinct causal pathways through which diabetes and obesity impact lipid metabolism.