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How the Tongue Can Be Used As A Possible Preliminary Diabetes Screening Tool

Jul 30, 2019
Editor: Steve Freed, R.PH., CDE

Author: Kassey  James, Pharm.D. Candidate, LECOM School of Pharmacy

A furry or bluish tongue may indicate type 2 diabetes, according to a recent study.

It is predicted that by the year 2030, 366 million people will have diabetes worldwide. Due to this epidemic, there is a growing need for additional diabetes screening tools. 

Traditional Chinese Medicine has used tongue diagnosis for centuries, so a recent study explored this method to discriminate between individuals with and without type 2 diabetes. This is the first study to examine the efficacy and value of tongue diagnosis in type 2 diabetes. This was an observational cross-sectional and cohort study that included 199 patients diagnosed with type 2 diabetes and 372 without type 2 diabetes. Comorbidities were not considered in this study. The tongue characteristics observed include: tongue color and shape, fur thickness and color, and the amount of saliva.

Patients with type 1 diabetes, renal disease, cancer, infection, pregnancy, and cerebrovascular disease were excluded from the type 2 diabetes group. The type 2 diabetes group was then divided into subgroups based on length of disease state < 15 years or ≥ 15 years and AIC value of <6.5% or >6.5%. Participants in the control group were sex and age matched to the type 2 diabetes group.

Due to the inconsistency involved with subjective diagnosis, an automated tongue diagnosis system was developed for this study. Tongue pictures were taken of each participant with personal details encrypted. Traditional Chinese Medicine uses 9 features for clinical tongue diagnosis, namely, tongue shape and color, fur thickness and color, amount of saliva, tongue fissure, ecchymosis, teeth marks, and red dots. Experienced Traditional Chinese Medicine practitioner opinions were integrated into the automated tongue diagnosis system.

Tongue features from each group were compared to determine significant differences and were analyzed using the chi-square test and independent t test. A one-way analysis of variance was used to compare group differences. The P value <.05 was considered statistically significant in this study.

Results revealed the type 2 diabetes group had a higher proportion of bluish tongue, and a significantly higher proportion of thick fur present on the tongue, compared to the control group. Regarding the participants in this study with type 2 diabetes, 58.5% possessed yellow colored fur on their tongues, and 47.1% had thick tongue fur. The subgroup of type 2 diabetics with a diagnosis ≥15 years displayed a higher amount of yellow fur color compared to those diagnosed for < 15 years, but without a significant difference. The control group had a greater number of red dots than the diabetes group. Although the percentage of patients with dry mouth was higher in the type 2 group, the difference was insignificant. The remaining tongue features did not vary significantly between the groups.

It is worth noting that yellow fur can result from poor oral hygiene and these factors were not considered in this study. Other limitations include: lack of consideration for comorbidities which may affect tongue appearance, and sublingual collateral vessels were not analyzed. Future studies will need to include participants with different disease states common in diabetes mellitus. 

In recent years, there have been numerous reports investigating tongue features and specific diseases, but this was the first to examine whether the tongue may indicate type 2 diabetes. Another study linked yellow fur color with pre-diabetes and diabetes mellitus. Based on the findings of these studies practitioners may consider tongue evaluations as a non-invasive diabetes screening tool.

Practice Pearls:

  • This study indicated a significantly higher presence of bluish tongue, yellow colored fur, and thick fur on the tongues of patients with type 2 diabetes.
  • To reduce the inconsistency of subjective diagnosis, an automated tongue diagnosis system should be used.
  • Oral hygiene and comorbidities were not considered in this study.



Hsu, Po-Chi, et al. The Tongue Features Associated with Type 2 Diabetes Mellitus. Medicine.

Wild S, Roglic G, Green A, et al. Global prevalence of diabetes: estimates for the year 2000 and projections for 2030. Diabetes Care 2004; 27:1047–53.


Kassey James, Pharm.D.Candidate, LECOM School of Pharmacy