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

“It’s better to light a candle than to curse the darkness” Dr. Younossi and the US Members of the Global NASH Council are to be congratulated for their effort(s) to raise awareness of the prognostic value of NAFLD and develop a simple and easy to use algorithm to help with the identification of high-risk patients by primary-care physicians and diabetologists1. However, it is important to emphasize 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 exist2. Recently, we have also proposed a pragmatic algorithm for the diagnosis and monitoring of NAFLD in individuals with and without T2DM2,3. To date, however, screening for NAFLD in high-risk groups of patients is not universally recommended by all scientific societies4-6. Singh et al. reported a high prevalence of advanced fibrosis by use of non-invasive fibrosis scores In a cohort of ~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 populations7. Other smaller studies performed in diabetes clinics reported the lack of sufficient accuracy of non-invasive fibrosis scores alone in identifying advanced fibrosis8,9. 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 pretest 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 fibrosis2,3. Therefore, T2DM patients with a raised score should undergo a second-line investigation to confirm advanced fibrosis. It is reasonable that combination of imaging and non-invasive tests may provide an alternative to optimize 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 In an unpublished analysis of 153 consecutive T2DM outpatients without known liver diseases, we found a poor diagnostic concordance (based on the Cohen's kappa coefficient)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, I think the article written by Dr. Younossi et al. is timely and of great clinical importance, especially for the management of T2DM patients, because NAFLD is frequently over-looked 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 diabetes2. In addition, I think the VCTE will become a mandatory technique in assessment and monitoring of NAFLD into routine diabetes care, because it may also allow a better choice of glucose-lowering agents, which exert beneficial effects on NAFLD and liver fibrosis10, such as pioglitazone, glucagon-like peptide-1 receptor agonists and, perhaps, also sodium-glucose co-transporter-2 inhibitors.