FLI is an algorithm combining body mass index (BMI), waist circumference (WC), gamma-glutamyl transferase (GGT), and triglyceride (TG) levels, and has been demonstrated to be a useful tool to predict the presence of Non-alcoholic fatty liver disease (NAFLD).
What is non-alcoholic fatty liver disease? NAFLD is a condition caused by a build-up of fat in the liver (free fatty acids and triglycerides infiltration in the hepatocytes) not due to alcohol consumption. It is often linked to being overweight or obese. Its development is associated with poor lifestyle choices such as poor eating habits and sedentary behavior, as well as visceral obesity, insulin resistance, and metabolic syndrome.
According to epidemiological and clinical evidence, the utilization of FLI during routine assessments in people with prediabetes contributes to the early targeting, and therefore treating, those at increased risk of developing T2D. A recent study pointed out that low baseline FLI scores are independently associated with prediabetes reversion.
FLI & diabetes
FLI correlates with insulin resistance and metabolic syndrome and it significantly predicts the risk of T2D in people with prediabetes. That is Liver fat accumulation has been recognized as a risk factor for the development of T2D.
The PREDAPS study, conducted in 1,142 Spanish adults with prediabetes attending primary care centers, demonstrated the utility of FLI to predict T2D development after 5 years of follow-up
In the Spanish PREDAPS study, an FLI >60 was independently associated with T2D incidence after 5 years of follow-up, independently of sex, age, and educational level.
In the Diabetes Remission Clinical Trial (DiRECT), early onset T2D was associated with increased liver fat accumulation. On the other hand, diabetes remission with concomitant β-cell recovery was associated with decreased liver and pancreas fat content following weight loss. Chronic β-cell exposure to excess fat has been long observed to induce β-cell damage and loss of function before incident T2D.
FLI for Diabetes Remission
Importantly, a FLI score of <30 with increased physical activity, and healthy dietary habits were independent factors associated with prediabetes reversion, suggesting that the absence of NAFLD and healthier lifestyle habits are protective of the progression to incident T2D.
Caloric restriction and weight loss have been associated with the reduction of ectopic fat, including liver triglycerides content, which in turn has been associated with restoration of β-cell function and increased hepatic insulin sensitivity, possibly reverting T2D.
Study results show that most patients who reverted to normoglycemia had normal fat liver content, and, consistent with the FLI equation, they also presented lower intrabdominal fat and a better metabolic profile than subjects who did not revert.
FLI may represent an ideal predictor for prediabetes reversion as it relates to intraabdominal fat accumulation and the cardiometabolic state of the patient, which affect the β-cell function and reduce insulin sensitivity time before the manifestation of hyperglycemia.
The fatty liver index (FLI) can also help to monitor the changes in glycemic status and the possibility of reverting to normoglycemia from prediabetes. Managing fatty liver and reducing FLI can help to prevent or delay the onset of type 2 diabetes and improve its outcomes.
Moreover, performing physical activity of 150 minutes/week or more and eating fruits and vegetables daily were also directly associated with an increased probability of reverting to normoglycemia within 5 years.
High fructose consumption is also associated with the development of NAFLD. Limiting or avoiding high-sugar foods and drinks, like processed foods and sodas, can also be helpful in preventing or slowing the progression of NAFLD.
FLI calculation
Fatty liver index (FLI) was calculated based on measurements of triglycerides, body mass index, waist circumference, and γ-glutamyl transferase. FLI is a surrogate measure of fatty liver.
Fatty liver index (FLI) = ey / (1 + ey) × 100
Where y = 0.953 × ln (TG) + 0.139 × BMI + 0.718 × ln (GGT) + 0.053 × WC – 15.745
Here, TG indicates triglyceride concentration in mg/dL; BMI indicates body mass index in kg/m2; GGT indicates γ-glutamyl transpeptidase in U/L; and WC indicates waist circumference in cm.
FLI Result Interpretation
The FLI scores vary between 1 and 100 and the original study set up the negative and positive likelihood cut-off points at 30 and 60. It has shown good diagnostic accuracy in detecting fatty liver.
- FLI scores below 30 indicate fatty liver should be ruled out;
- FLI scores between 30 and below 60 indicate indeterminate risk remains inconclusive in which fatty liver could not be ruled in or out;
- FLI scores of 60 and above indicate a high risk in which a fatty liver is confirmed.
Reference: The Fatty Liver Index: a simple and accurate predictor of hepatic steatosis in the general population. BMC Gastroenterol. 2006; 6:33.