Heterogeneous associations of insoluble dietary fibre intake with subsequent glycosylated Hb levels among Chinese adults with type 2 diabetes: a quantile regression approach

Abstract

Dietary fibre intake has been suggested to reduce blood glucose levels in diabetic patients, particularly when glycosylated Hb (HbA 1c ) levels are high. In the present study, we used a quantile regression (QR) approach to characterise the possible heterogeneous associations of dietary fibre intake with HbA 1c levels in Chinese diabetic patients. A total of 497 diabetic patients participated in the baseline survey in 2006 and in the follow-up survey in 2011, both of which were conducted in Pudong New Area of Shanghai, China. Structured in-person interviews were conducted to collect information on demographic characteristics and lifestyle factors. Dietary intake was assessed using a validated FFQ. Blood samples were collected during the interviews for biochemical assays. QR models were used to examine the heterogeneous associations of dietary factors with HbA 1c levels. A significant marginal association of insoluble dietary fibre intake with subsequent HbA 1c levels was observed only when the HbA 1c level was over 6·8 %. The associations appeared to be greater when the quantile levels of HbA 1c were higher. The coefficient estimates were 20·174 (95 % CI 2 0·433, 20·025) at the quantile of 0·60, 20·200 (95 % CI 20·306, 20·008) at 0·70, 20·221 (95 % CI 20·426, 20·117) at 0·80, and 20·389 (95 % CI 20·516, 20·018) at 0·90. A similar pattern was observed for the associations of dietary glycaemic index (GI) value with HbA 1c levels. In conclusion, the present results indicate that the associations of insoluble dietary fibre intake and GI value with subsequent HbA 1c levels depend on glycaemic control status in Chinese diabetic patients. More studies are required to confirm our findings.

Insoluble Dietary Fiber from Pear Pomace Can Prevent High-Fat Diet-Induced Obesity in Rats Mainly by Improving the Structure of the Gut Microbiota

“…Isken et al [11] reported that supplementing the diet with insoluble cereal fiber resulted in significantly lower weight gain and improved insulin sensitivity. Tan et al [12] also found the associations of IDF intake and glycemic index value with subsequent HbA1c levels. In spite of these efforts, whether and how IDF affects the gut microbiota, key lipometabolism, and satiety hormone secretion is largely unknown.…”

Quantile regression reaches the parts that mean regression may not: insoluble dietary fibre and glycaemic index in type 2 diabetes

“…no assumptions are made about a relationship being either linear or curvilinear in any pre-specified form; meanwhile, intercepts and slopes are not assumed constant from one quantile to another. Interestingly, the observations from Tan et al ( 1 ) indicate a possible broadly inverted U-shaped relationship for the size of associations for the decrease in HbA 1c concentrations with higher insoluble fibre intake (their Fig. 1) and a possible broad U-shaped association between the increase in HbA 1c concentrations and higher GI in the upper quantiles (their Fig.…”

“…For many a reader, clarity is likely to appear weaker still because QR is currently not a familiar statistical procedure. Hence, considering these weaknesses together, Tan et al ’s study ( 1 ) inevitably informs us about the uncertain strengths of the association (probably underestimates) between the change in HbA 1c concentrations over 5 years and insoluble dietary fibre and GI intakes at each possible quantile of HbA 1c (their ( 1 ) Table 2 and Figs. 1 and 2).…”

“…Some differences exist in the observations made between their Chinese patients with T2D (5-year follow-up in prospective cohorts, which are non-randomised) ( 1 ) and counterparts of Western ethnicities in whom fibre and GI acted independently ( < 6-month follow-up in randomised controlled trials) ( 6 ) , but their findings are similar. Moreover, results of these publications are consistent with other studies (6-year follow-up in prospective cohorts) showing that both cereal fibre and GI via glycaemic load (GL), independently of one another, associate with the incidence of T2D ( 16 , 17 ) .…”

“…It is increasingly evident from comparisons among interventional studies ( 6 , 10 ) , among prospective cohort studies ( 11 ) , and within the prospective cohort study of Tan et al ( 1 ) that human nutrition studies are more complex than catered for by the regularly used MR and meta-analysis without appropriate modelling (which may include quotients or products of predictor variables). Generalising from these observations, no two studies examining the same issue from within or among laboratories can be assumed alike, and no two participants examined within a study can be assumed alike even when categorised similarly for clinical purposes.…”