Taste perception and food preferences in patients with diabetic foot ulcers before and after hyperbaric oxygen therapy

Type 2 diabetes, often linked to poor nutrition and sedentary lifestyles, significantly impacts taste perception and eating behaviors. Oral complications, such as Candida-associated denture stomatitis, burning mouth syndrome, and glossitis, are more prevalent in type 2 diabetes patients and can distort taste. This chemosensory dysfunction is associated with the severity of vascular complications, peripheral neuropathy, and microalbuminuria. Hyperbaric oxygen therapy (HBOT), involving breathing 100% oxygen at increased pressure, is used to treat diabetic foot ulcers. While HBOT has shown benefits in wound healing, its impact on taste and food preferences remains unclear. This study investigates whether HBOT affects taste perception and food preferences in patients with diabetic foot ulcers, given the strong link between diabetic complications and diet. Previous research hinted at beneficial effects of HBOT on taste in a heterogeneous patient group, but a focused investigation on diabetic foot ulcer patients is warranted.

Existing literature highlights the relationship between type 2 diabetes and altered taste perception. Studies have shown taste dysfunction in diabetic patients, affecting various basic tastes, including sweet, salty, umami, sour, and bitter. The impact of these taste disturbances on dietary habits and the overall health of diabetic individuals has been a focus of several investigations. The effectiveness of various interventions such as zinc supplementation, intranasal theophylline, and magnetic nerve stimulation on taste disorders has also been examined, with the most significant improvement observed when treating the underlying condition causing the taste disturbance. Studies on the effect of HBOT on taste perception are limited, with some showing potential benefits in patients with non-healing wounds.

This study employed a comparative design involving three groups: 75 healthy controls (Group C), 23 patients with diabetic foot ulcers before HBOT (Group Db), and the same 23 patients after 25-30 HBOT treatments (Group Da). Patients were recruited from a larger project investigating HBOT's effect on taste and food preferences. Inclusion criteria included having a condition warranting HBOT and eligibility for National Health Fund reimbursement, while exclusion criteria encompassed conditions precluding HBOT, urgent HBOT needs, oral injuries, communication difficulties, or refusal to participate. Groups C and Db were age and BMI matched. The study protocol was approved by the Bioethics Committee of the Medical University of Silesia. Participants provided written informed consent. Group C underwent gustatory testing once over two consecutive days, while Group D participated twice—before and after HBOT. Gustatory tests, following ISO 3972 procedures, assessed taste recognition thresholds, taste intensity, and hedonic response to five basic tastes (sweet, salty, umami, sour, bitter) using various concentrations of aqueous solutions. Food preference tests involved rating the pleasantness of various food items from photographs using a 10-cm visual analog scale. Data analysis utilized Mann-Whitney U tests (Group C vs. Group Db) and Wilcoxon signed-rank tests (Group Db vs. Group Da). Statistical significance was set at p<0.05.

Before HBOT, patients with diabetic foot ulcers (Group Db) exhibited significantly higher taste recognition thresholds for all five basic tastes compared to healthy controls (Group C) (p<0.05 for salty, p<0.01 for sweet, umami, and bitter, p<0.001 for sour). Group C also showed higher taste intensity for monosodium glutamate (0.1% and 1.0%), citric acid (0.02%), and quinine hydrochloride (0.002%) and more negative hedonic responses for sodium chloride (0.18%), monosodium glutamate (0.3%), and citric acid (0.1%). Group C experienced less pleasure from sour and salty foods than Group Db. Following HBOT (Group Da), recognition thresholds for umami and sour tastes decreased significantly compared to Group Db (p<0.05). Taste intensity increased significantly for monosodium glutamate (0.1%, 0.3%, and 1.0%) after HBOT. Post-HBOT, patients reported reduced pleasure from chocolate and crisps (p<0.05 for chocolate, p=0.050 for crisps).

The study demonstrated impaired taste perception across all five basic tastes in patients with diabetic foot ulcers before HBOT, aligning with other research indicating that taste dysfunction is common in type 2 diabetes. The increased preference for salty foods in the diabetic group before HBOT aligns with other findings indicating altered salt taste recognition thresholds. The increase in umami and sour taste sensitivity after HBOT suggests a positive effect of the therapy on chemosensory function. The reduced pleasure from chocolate and crisps post-HBOT could be related to increased umami sensitivity, as these foods often contain umami flavor enhancers. However, considering the wide-ranging effects of HBOT on the body, other factors may influence this observation. The lack of significant changes in hedonic response for suprathreshold concentrations of basic tastes post-HBOT warrants further investigation. The study's findings highlight the complex interplay between taste perception, food preferences, and the metabolic effects of HBOT in patients with diabetes.

Patients with advanced type 2 diabetes and diabetic foot ulcers exhibit impaired taste and altered food preferences. HBOT improves umami and sour taste sensitivity and reduces the enjoyment of chocolate and crisps. Further research is crucial to understand the clinical implications of these changes and how HBOT's effects vary across different stages of diabetic complications. Longitudinal studies tracking dietary changes post-HBOT are needed to fully assess the therapy's impact on nutritional behavior.

The study focused on patients with advanced diabetes and existing complications, potentially limiting the generalizability of findings to patients with less severe disease. The lack of HbA1c measurements prevents a complete assessment of glycemic control and its relation to taste perception. The subjective nature of food preference assessments might introduce bias. The relatively small sample size may limit statistical power.