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Improved NAFLD reduces type 2 diabetes incidence
Nonalcoholic fatty liver disease, or NAFLD, is associated with type 2 diabetes, and improvement of NAFLD is associated with a reduction in the incidence of type 2 diabetes, according to recent study findings published in Diabetes Care.
“The current study showed a positive association between NAFLD improvement and [type 2 diabetes] incidence reduction independent of the potential confounders,” the researchers wrote. “The possible explanations are that 1) NAFLD improvement reduced [type 2 diabetes] incidence and 2) other factors (eg, lifestyle modification) affected both NAFLD improvement and [type 2 diabetes] risk reduction.”
Hajime Yamazaki, MD, of Teine Keijinkai Hospital in Japan, and colleagues evaluated data from 3,074 adults who attended Keijinkai Maruyama Clinic in Japan and received an abdominal ultrasound health check twice between 2000 and 2012, with more than 10 years between checks. Participants were divided into two groups: those with NAFLD (n = 728; 611 men) and without NAFLD (n = 2,346; 1,255 women). The group with NAFLD was further divided into those who improved (n = 110) and those who sustained (n = 618) based on the second health check.
Hajime Yamazaki
During follow-up, there was a 6.1% incidence of type 2 diabetes among all participants; the incidence was higher in the NAFLD group (16.1%) compared with the group without NAFLD (3.1%). After adjustment for age, sex, BMI, impaired fasting glucose, family history of diabetes, dyslipidemia, hypertension and physical activity, type 2 diabetes incidence was associated with NAFLD at baseline (OR = 2.37; 95% CI, 1.6-3.52).
Researchers found that the sustained NAFLD group had a higher type 2 diabetes incidence (17.8%) compared with the improved group (6.4%). After adjustment for age, sex, BMI, IFG, family history of diabetes, dyslipidemia, hypertension and physical activity, a reduced type 2 diabetes incidence was associated with improved NAFLD (OR = 0.27; 95% CI, 0.12-0.61).
“NAFLD is a significant risk factor for type 2 diabetes, and NAFLD improvement may reduce type 2 diabetes incidence,” Yamazaki told Endocrine Today. “Clinicians should be aware of the importance of NAFLD on type 2 diabetes prevention.” – by Amber Cox
Disclosure: The researchers report no relevant financial disclosures.
Perspective
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The study by Yamazaki and colleagues reporting a much higher prevalence of type 2 diabetes, and of new onset diabetes, in a Japanese population with nonalcoholic fatty liver disease (NAFLD) followed for at least 10 years, highlight the metabolic risks of this condition, in addition to the known risk of cirrhosis, hepatocellular carcinoma and cardiovascular disease. Stressing the clinical value of reversing NAFLD over time, those without NAFLD on repeat ultrasound (110 out of 728) had about significantly less type 2 diabetes (6.4 vs. 17.8%; (multivariate OR = 0.27; 95% CI, 0.12-0.61).
Limitations of the study included its retrospective nature, that groups were poorly matched for baseline characteristics (ie, worse family history of diabetes and metabolic profile in those with NAFLD), lack of information on diabetes medications, or how liver fat improved in many despite an increase in BMI. Another shortcoming was the lack of a baseline or follow-up oral glucose tolerance test (OGTT) to appropriately classify patients for diabetes. More importantly, liver ultrasound is known to be an insensitive technique to diagnose, or follow-up over time, patients with NAFLD, having modest correlation with the gold-standard magnetic resonance and spectroscopy (1H-MRS) technique or a liver biopsy (see recent publication by Bril, et al. Liver Int. 2015;doi: 10.1111/liv.12840.).
However, the findings are likely true beyond these limitations and the study is of value to increase awareness about recognizing NAFLD as a risk factor for type 2 diabetes in high-risk patients, and that its reversal over time may ameliorate the risk of developing type 2 diabetes. These findings may encourage routine screening and intervention, which I believe will become standard in the future to deliver better care to many of these patients.