Lisa Glass is a Staff Physician, and Grace Su is Chief of Gastroenterology and Associate Chief of Medicine, both at VA Ann Arbor Healthcare System. Christine Hunt is a Physician Affiliate and Director of the Cooperative Studies Program Epidemiology Centers at Durham VAMC in North Carolina. Michael Fuchs is Chief of Hepatology and Liver Transplantation at Hunter Holmes McGuire VAMC. Christine Hunt is an Adjunct Associate Professor of Medicine at Duke University Medical Center in Durham. Lisa Glass is an Assistant Professor and Grace Su is a Professor of Medicine, both at the University of Michigan Medical School in Ann Arbor. Michael Fuchs is Professor of Medicine at Virginia Commonwealth University in Richmond. Correspondence: Lisa Glass (lisaglas@med.umich.edu)
Author disclosures The authors report no actual or potential conflicts of interest with regard to this article.
Disclaimer The opinions expressed herein are those of the authors and do not necessarily reflect those of Federal Practitioner, Frontline Medical Communications Inc., the US Government, or any of its agencies. This article may discuss unlabeled or investigational use of certain drugs. Please review the complete prescribing information for specific drugs or drug combinations—including indications, contraindications, warnings, and adverse effects—before administering pharmacologic therapy to patients.
Patients with T2DM and NAFLD are at increased risk of progressive liver disease and have increased rates of NASH, cirrhosis, and HCC. In a paired-biopsy study, the development of T2DM was the strongest predictor of progression of NASH and hepatic fibrosis.20 This fibrosis progression can easily go undetected, as NASH can be present even with normal aminotransferases. This increased risk of fibrosis progression in the setting of comorbid T2DM is clinically important, as it is the severity of fibrosis that predicts all-cause and liver-related mortality in patients with NAFLD/NASH.21,22 In fact, the prevalence of biopsy-proven NASH in overweight/obese patients with DM with normal liver aminotransferases (defined as aspartate aminotransferase and alanine aminotransferase < 40 U/L) was found to be 58%.23 Because chronic liver disease, including NAFLD, is underrecognized in the “healthy population” used to establish normal aminotransferase levels, more recent AASLD and ACG guidelines now define normal aminotransferase levels as < 35 U/L for males and < 25 U/L for females.24 These stricter cutoffs are based on populations with normal BMI and negative testing for chronic liver diseases.24 The lower cutoffs may improve recognition of progressive liver disease in NAFLD and NASH patients.
Medications used in the treatment of T2DM, such as metformin, pioglitazone, and liraglutide, have been studied in patients with biopsy-proven NASH. The initial data showing histologic improvement in NAFLD patients taking metformin was more likely related to the associated weight loss in the treatment group. In a study by Loomba and colleagues the improvement in the NAFLD activity score was only seen in patients who lost ≥ 5% of their total body weight.25 Pioglitazone is a PPAR-γ agonist that helps regulate glucose and lipid metabolism as well as inflammation. Pioglitazone helps adipose tissue, hepatocytes, and muscle cells restore insulin sensitivity. A recent trial in 100 patients with prediabetes or T2DM as well as NASH showed that 36 weeks of pioglitazone treatment was associated with significant improvements in steatosis, inflammation, and most important, in stage of fibrosis compared with that of placebo.26
Glucagon-like peptide-1 (GLP-1) receptor agonists, such as liraglutide, have effects on lipid and glucose metabolism as well. They can lower glucose levels by increasing insulin secretion, reducing glucagon concentration, suppressing appetite (resulting in weight loss), and increasing sensitivity to insulin in hepatocytes and adipocytes. Liraglutide has been studied in patients with NASH both with and without DM, and results of the largest study to date show that it is associated with significant improvement in hepatic inflammation compared with that of placebo.27 Additional phase 3 clinical trials are currently underway.
Current AASLD guidelines do not recommend routine screening for NAFLD, even among high-risk patients, such as patients with DM.18 This is due to the widespread prevalence of NAFLD, the unclear utility of diagnostic tests, and limited efficacy of available treatment. Lifestyle modification to achieve weight loss remains the backbone of management, and rates of successful adherence are low.28 Contrary to this, EASL guidelines state that NAFLD screening with ultrasound even in patients with normal liver enzymes should be performed in high-risk patients with T2DM.19
Once detected, T2DM should be diligently treated in patients with NAFLD, and pioglitazone may be considered in patients with biopsy-proven NASH per AASLD guidelines.18 Pioglitazone has been studied in patients with biopsy-proven NASH both with and without DM and has been associated with significant resolution of NASH, as well as improvement in histologic changes of NASH and improvement in fibrosis.29,30 Because of potential medication AEs, including a mean weight gain of 2.5 kg to 4.7 kg in trials of 12- to 36-months’ duration, as well as potential bone loss in women, discussions about the risks and benefits of treatment should occur prior to treatment initiation.18 Additionally, pioglitazone is not safe in the setting of left ventricular heart failure. Future studies may point to the utility of other DM medications, such as GLP-receptor agonists.
