GSTM1 and diabetes mellitus: We found significantly lower levels of CRP in carriers of the GSTM1 null mutation in patients with diabetes only; and higher levels of CRP in carriers of the GSTT1 null mutation; the latter differed from results in patients with diabetes and smokers (lower CRP among carriers of the GSTT1 null mutation); (Hayek et al. 2006; Miller et al. 2003) however these participants were otherwise healthy.