The following confounders were retained: age (per 10-year increment), HIV transmission group (men who had sex with men versus all other patients), current CD4 T cell count (after log2 transformation), haemoglobin level (after log2 transformation), BMI (<21, 21–26, ≥27 kg/m2), smoking status (never, ceased ≤3 years, ceased >3 years, current), anti-HCV antibodies positivity (yes/no), HBs antigen positivity (yes/no), diabetes (yes/no) and hypertension (yes/no). The gene discussed is CD4; the disease is diabetes mellitus.