Fig. 2
Two-sample Mendelian randomisation results of the potential causal effect of lifetime smoking on glycaemic traits. Results from the main IVW two-sample Mendelian randomisation (MR) analysis of lifetime smoking on fasting glucose, fasting insulin and HbA1c and the sensitivity analysis results from MR Egger, SIMEX, weighted median, PRESSO and GSMR analyses. Results are the difference in mean fasting glucose (mmol/l), fasting insulin (pmol/l) and HbA1c (NGSP percent or equivalent) per 1 SD higher lifetime smoking index (LSI) value, with 95% confidence intervals (CI), noting that 1 SD higher LSI value is equivalent to an individual smoking 20 cigarettes per day for 15 years and stopping 17 years ago or smoking 60 cigarettes a day for 13 years and stopping 22 years ago. Multivariable Mendelian randomisation analyses including body mass index for the outcomes of fasting glucose and fasting insulin are not presented here but results with this approach were in line with the main IVW results. SNP single nucleotide polymorphism, IVW inverse-variance weighted, SIMEX simulation extrapolation, PRESSO pleiotropy RESidual sum and outlier, GSMR generalised summary-data-based Mendelian randomization.
