Editorial: a diabetologist's perspective on the diagnosis and monitoring of NAFLD

Dr Younossi and the US members of the Global NASH Council are to be congratulated for their effort to raise awareness of the prognostic value of NAFLD and to develop a simple and easy-to-use algorithm to help with the identification of high-risk patients by primary-care physicians and diabetologists.1 However, it is important to emphasise that an intense debate on aspects of similar algorithms is ongoing and that a validated, widely accepted algorithm for the diagnosis and monitoring of NAFLD in patients with type 2 diabetes mellitus (T2DM) does not yet exist.2 Recently, we have also proposed a pragmatic algorithm for the diagnosis and monitoring of NAFLD in individuals with and without T2DM.2,3 To date, however, screening for NAFLD in high-risk groups of individuals is not universally recommended by scientific societies.4-6 Singh et al reported a high prevalence of advanced fibrosis with the use of non-invasive fibrosis scores. In approximately 121 500 patients with T2DM, however, the substantial variability among the findings provided by such scores (ranging from 8.4% with the use of FIB-4 score to nearly 35% with the NAFLD fibrosis score [NFS]) strongly supports the need for their further validation in T2DM populations.7 Other smaller studies performed in diabetes clinics reported the lack of sufficient accuracy of non-invasive fibrosis scores alone in identifying advanced fibrosis.8,9 This implies that these scores should be used with caution in people with T2DM, taking into account the characteristics of the target population (i.e., in whom the pre-test probability of advanced fibrosis is lower than that in hepatology clinic patients). In this setting, the major value of these non-invasive fibrosis scores is to exclude rather than diagnose advanced fibrosis.2,3 Therefore, T2DM patients with a raised score should undergo a second-line investigation to confirm advanced fibrosis. It is reasonable that the combination of imaging and non-invasive tests may provide an alternative to optimise the non-invasive diagnosis of advanced fibrosis. In particular, further work is needed to confirm whether combining vibration-controlled transient elastography (VCTE) and non-invasive tests can improve diagnostic accuracy in identifying advanced fibrosis in T2DM. In an unpublished analysis of 153 consecutive T2DM outpatients without known liver diseases, we found a poor diagnostic concordance (based on the Cohen's kappa coefficient) between VCTE-measured liver stiffness and FIB-4 or NFS. That said, the article written by Dr Younossi et al is timely and of great clinical importance, especially in the management of T2DM patients, because NAFLD is frequently overlooked in routine diabetes care (given that most of these NAFLD patients have fairly normal serum aminotransferase levels). The presence of NAFLD has implications not only for liver disease progression, but also for chronic vascular complications of diabetes.2 In addition, VCTE will become a mandatory technique in assessment and monitoring of NAFLD in routine diabetes care, because it may also allow a better choice of anti-hyperglycemic agents, which exert beneficial effects on NAFLD and liver fibrosis,10 such as pioglitazone, glucagon-like peptide-1 receptor agonists and, perhaps, also sodium-glucose co-transporter-2 inhibitors.