Mendelian randomization analyses suggest a causal role for circulating GIP and IL-1RA levels in homeostatic model assessment-derived measures of β-cell function and insulin sensitivity in Africans without type 2 diabetes

Table 3 Genetic instruments for all cytokines and hormones at a 5 × 10⁻⁷ p-value threshold

Cytokine/hormone	Number of participants	Number of genetic instruments	Cumulative F-statistic	Variance explained (R²)	Power HOMA-S^a	Power HOMA-B^a	Power T2D^a
Adipsin	4854	3	74.8	0.090	0.89	0.88	0.99
Leptin	4914	2	13.6	0.011	0.23	0.23	0.34
Visfatin	4853	2	19.9	0.017	0.28	0.28	0.49
PAI-1	4914	3	20.9	0.026	0.39	0.38	0.66
GIP	4956	7	15.4	0.042	0.57	0.58	0.86
GLP-1	4913	3	15.3	0.018	0.28	0.27	0.51
Ghrelin	4923	2	30.5	0.025	0.38	0.38	0.65
Resistin	4894	7	62.4	0.159	0.99	0.99	1.00
IL-6	1330	1	24.3	0.032	0.46	0.45	0.75
IL-10	1095	2	24.0	0.060	0.74	0.74	0.95
IL-1RA	1416	3	20.5	0.069	0.80	0.79	0.97

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