Hepatitis C virus (HCV) infection and diabetes mellitus are two major public health problems that cause devastating health and financial burdens worldwide. Diabetes can be classified into two major types: type 1 diabetes mellitus (T1DM) and T2DM. T2DM is a common endocrine disorder that encompasses multifactorial mechanisms, and T1DM is an immunologically mediated disease. Many epidemiological studies have shown an association between T2DM and chronic hepatitis C (CHC) infection. The processes through which CHC is associated with T2DM seem to involve direct viral effects, insulin resistance, proinflammatory cytokines, chemokines, and other immune-mediated mechanisms. Few data have been reported on the association of CHC and T1DM and reports on the potential association between T1DM and acute HCV infection are even rarer. A small number of studies indicate that interferon-α therapy can stimulate pancreatic autoimmunity and in certain cases lead to the development of T1DM. Diabetes and CHC have important interactions. Diabetic CHC patients have an increased risk of developing cirrhosis and hepatocellular carcinoma compared with non-diabetic CHC subjects. However, clinical trials on HCV-positive patients have reported improvements in glucose metabolism after antiviral treatment. Further studies are needed to improve prevention policies and to foster adequate and cost-effective programmes for the surveillance and treatment of diabetic CHC patients.

To investigate the plasma homocysteine concentrations with regard to nutritional, metabolic and genetic factors and to find out the frequency and impact of thermolabile methylenetetrahydrofolate reductase (T-MTHFR) polymorphism in patients with type 2 diabetes mellitus.

A cross-sectional study.

A total of 94 subjects with type 2 diabetes mellitus and 91 healthy age- and sex-matched nonsmoking volunteers were recruited.

Age, sex, duration and complications of diabetes mellitus, metabolic variables, fasting plasma homocysteine levels, and presence of T-MTHFR polymorphism were evaluated for all participants. Presence of T-MTHFR polymorphism was analysed to define any possible role in diabetes progress, complications and metabolic milieu.

Fasting homocysteine levels were similar in diabetic patients and controls. Prevalence of homozygous polymorphism of thermolabile MTHFR gene (TT) was encountered more frequently in patients with diabetes mellitus than the healthy controls (P = 0.004). Subgrouping of the patients with respect to MTHFR genotype revealed similar metabolic variables and frequency of chronic complications of diabetes mellitus in groups. Patients with TT genotype revealed longer diabetes duration when compared with the patients having heterozygous mutation of thermolabile MTHFR or normal homozygous MTHFR genotypes (P = 0.046).

Type 2 diabetic patients have similar fasting plasma homocysteine levels with that of age- and sex-matched healthy people. There is no correlation between diabetic complications and this amino acid metabolite. On the contrary, thermolabile variant of MTHFR genotype is found to be more frequent in diabetic patients especially in those who have experienced a longer duration of disease.