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- Yaghootkar, Hanieh, et al.
(författare)
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Mendelian randomization studies do not support a causal role for reduced circulating adiponectin levels in insulin resistance and type 2 diabetes.
- 2013
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Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 62:10, s. 3589-3598
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Tidskriftsartikel (refereegranskat)abstract
- Adiponectin is strongly inversely associated with insulin resistance and type 2 diabetes, but its causal role remains controversial. We used a Mendelian randomization approach to test the hypothesis that adiponectin causally influences insulin resistance and type 2 diabetes. We used genetic variants at the ADIPOQ gene as instruments to calculate a regression slope between adiponectin levels and metabolic traits (up to 31,000 individuals) and a combination of instrumental variables and summary statistics-based genetic risk scores to test the associations with gold-standard measures of insulin sensitivity (2,969 individuals) and type 2 diabetes (15,960 case subjects and 64,731 control subjects). In conventional regression analyses, a 1-SD decrease in adiponectin levels was correlated with a 0.31-SD (95% CI 0.26-0.35) increase in fasting insulin, a 0.34-SD (0.30-0.38) decrease in insulin sensitivity, and a type 2 diabetes odds ratio (OR) of 1.75 (1.47-2.13). The instrumental variable analysis revealed no evidence of a causal association between genetically lower circulating adiponectin and higher fasting insulin (0.02 SD; 95% CI -0.07 to 0.11; N = 29,771), nominal evidence of a causal relationship with lower insulin sensitivity (-0.20 SD; 95% CI -0.38 to -0.02; N = 1,860), and no evidence of a relationship with type 2 diabetes (OR 0.94; 95% CI 0.75-1.19; N = 2,777 case subjects and 13,011 control subjects). Using the ADIPOQ summary statistics genetic risk scores, we found no evidence of an association between adiponectin-lowering alleles and insulin sensitivity (effect per weighted adiponectin-lowering allele: -0.03 SD; 95% CI -0.07 to 0.01; N = 2,969) or type 2 diabetes (OR per weighted adiponectin-lowering allele: 0.99; 95% CI 0.95-1.04; 15,960 case subjects vs. 64,731 control subjects). These results do not provide any consistent evidence that interventions aimed at increasing adiponectin levels will improve insulin sensitivity or risk of type 2 diabetes.
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| 2. |
- Yaghootkar, Hanieh, et al.
(författare)
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Genetic evidence for a normal-weight "metabolically obese" phenotype linking insulin resistance, hypertension, coronary artery disease and type 2 diabetes.
- 2014
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Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 63:12, s. 4369-77
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Tidskriftsartikel (refereegranskat)abstract
- The mechanisms that predispose to hypertension, coronary artery disease (CAD) and type 2 diabetes (T2D) in individuals of normal weight are poorly understood. In contrast, in monogenic primary lipodystrophy - a reduction in subcutaneous adipose tissue - it is clear that it is adipose dysfunction that causes severe insulin resistance (IR), hypertension, coronary artery disease and type 2 diabetes. We aimed to test the hypothesis that common alleles associated with insulin resistance also influence the wider clinical and biochemical profile of monogenic insulin resistance. We selected 19 common genetic variants associated with fasting insulin based measures of insulin resistance. We used hierarchical clustering and results from genome wide association studies of 8 non-disease outcomes of monogenic insulin resistance, to group these variants. We analysed genetic risk scores against disease outcomes including 12,171 T2D cases, 40,365 CAD cases and 69,828 individuals with blood pressure measurements. Hierarchical clustering identified 11 variants associated with a metabolic profile consistent with a common, subtle, form of lipodystrophy. A genetic risk score consisting of these 11 IR risk alleles was associated with higher triglycerides (ß=0.018; p=4x10(-29)), lower HDL cholesterol (ß=-0.020; p=7x10(-37)), greater hepatic steatosis (ß=0.021; p=3x10(-4)) higher alanine transaminase (ß=0.002; p=3x10(-5)), lower SHBG (ß=-0.010; p=9x10(-13)) and lower adiponectin (ß=-0.015; p=2x10(-26)). The same risk alleles were associated with lower BMI (per-allele ß=-0.008; p=7x10(-8)), and increased visceral-to-subcutaneous adipose tissue ratio (ß=-0.015; p=6x10(-7)). Individuals carrying >= 17 fasting insulin raising alleles (5.5% population) were slimmer (0.30 kgm(-2)) but at increased risk of T2D (odds ratio [OR] 1.46, per-allele p=5x10(-13)), CAD (OR 1.12, per-allele p=1x10(-5)), and increased blood pressure (systolic and diastolic blood pressure of 1.21 mmHg (per-allele p=2x10(-5)), and 0.67 mmHg (per-allele p=2x10(-4)), respectively, compared to individuals carrying <=9 risk alleles (5.5% population). Our results provide genetic evidence for a link between the three diseases of the "metabolic syndrome" and point to reduced subcutaneous adiposity as a central mechanism.
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