Impaired taste sensation in type 2 diabetic patients without chronic complications: a case-control study

Purpose Few and contradictory data suggest changes in taste perception in type 2 diabetes (T2DM), potentially altering food choices. We, therefore, analyzed taste recognition thresholds in T2DM patients with good metabolic control and free of conditions potentially impacting on taste, compared with age-, body mass index-, and sex-matched normoglycemic controls. Methods An ascending-concentration method was used, employing sucrose (sweet), sodium chloride (salty), citric acid (sour), and quinine hydrochloride (bitter), diluted in increasing concentration solutions. The recognition threshold was the lowest concentration of correct taste identification. Results The recognition thresholds for the four tastes were higher in T2DM patients. In a multiple regression model, T2DM [beta = 0.95; 95% CI 0.32-1.58; p = 0.004 (salty); beta = 0.61; 0.19-1.03; p = 0.006 (sweet); beta = 0.78; 0.15-1.40; p = 0.016 (sour); beta = 0.74; 0.22-1.25; p = 0.006 (bitter)] and waist circumference [beta = 0.05; 0.01-0.08; p = 0.012 (salty); beta = 0.03; 0.01-0.05; p = 0.020 (sweet); beta = 0.04; 0.01-0.08; p = 0.020 (sour); beta = 0.04; 0.01-0.07; p = 0.007 (bitter)] were associated with the recognition thresholds. Age was associated with salty (beta = 0.06; 0.01-0.12; p = 0.027) and BMI with sweet thresholds (beta = 0.06; 0.01-0.11; p = 0.019). Conclusions Taste recognition thresholds were higher in uncomplicated T2DM, and central obesity was significantly associated with this impairment. Hypogeusia may be an early sign of diabetic neuropathy and be implicated in the poor compliance of these patients to dietary recommendations.