Review for 10.1186/1471-230X-10-56 (2010)

Reviewer's report
Title:Nine-year incident diabetes is predicted by fatty liver indices: The French
D.E.S.I.R. study
Version: 1Date:23 February 2010
Reviewer: Monica Nannipieri
Reviewer's report:
The authors evaluated the predictive power of two recent indexes of fatty liver
(FLI and NAFLD-FLS) on incident diabetes in a French population. They
concluded that these fatty liver indexes, that could be useful in evaluating the
extent of fatty liver disease, are also predictive of incident diabetes.
The study was carried out in a very large population, in which the cases of
incident diabetes in a period of 9-years, were potentially sufficient to looking for a
predictive marker of incident diabetes and it could be potentially interesting to
identify simple clinical tools in predicting diabetes development. However, there
are several important limitations and flaws in this study that strongly reduce the
strength of reported results.
1) As stated by the authors themselves, definition of fatty liver used in this study
was only based on surrogate indexes without any data from scanning device. In
the absence of such fundamental direct data on liver state it is hard to give any
conclusion on validation of the above indexes of fatty liver to predict incident
diabetes
2) The utilized NAFLD-FLS index includes many parameters of metabolic
syndrome such as central obesity, lipid concentration and plasma insulin
concentrations that are per se important predictors for incident diabetes.
Therefore, if NAFLD-FLS index could be considered an acceptable index for fatty
liver prediction it does not appear to be the same for predicting diabetes.
Moreover, although the authors state that “the term in type 2 diabetes does not
contribute in our study”, the use of such an index that includes predefinition of
presence of diabetes to evaluate incident diabetes is strongly questionable
3) The new finding of the study is somewhat limited by the knowledge that some
previous studies had already demonstrated that aminotransferases correlate to
type 2 diabetes and predict incident diabetes per se (The Mexico City Diabetes
Study), other than as well as plasma glucose and insulin.
4) In the present study the authors tried to identify a new predictor of diabetes
useful for general population; however they did not study a general population,
but only volunteers; this could have introduced some selection-bias
5) The population was not screened for fundamental biochemical parameters
such as markers of viral hepatitis; this limitation clearly affects the strength of
reported results.
6) The Authors stated that population was evaluated according to the degree of
physical activity and to where the activity was done (see Measures of Inclusion
Section page 5); no criteria utilized to define physical activity were, on the
contrary, reported; in the absence of definition, the interpretation of data as
reported in Table 1 (Intense physical activity) and in Results Section (see page 8)
is strongly limited. The same for the smoking habits: what criteria were utilized?
(Smoker non smoker?; other?)
7) The studied population shows clear unbalance as far as Women/Men
distribution according to Fatty liver index (see Table 1). Actually, 73% of women
showed a fatty liver index < 20 vs 32% as obtained in men. This point should be
carefully discussed.
8) Data on FLI classes are shown as mean +/- SD; this form of presentation of
data is questionable in the absence of data on distribution.
Minor:
The manuscript needs important revision for English.
Level of interest: An article of insufficient interest to warrant publication in a
scientific/medical journal
Quality of written English: Needs some language corrections before being
published
Statistical review: Yes, but I do not feel adequately qualified to assess the
statistics.
Declaration of competing interests:
I declare that I have no competing interests