Duration of Type 2 Diabetes Mellitus Alters Orosensory Detection of Sweet and Fat: Insights from a Cross-Sectional Study in a North African Population

<b>Background:</b> Gustatory dysfunction represents an underrecognized complication that may influence dietary behaviors and metabolic control. Previous investigations have suggested alterations in taste in patients with diabetes, yet the relationship between disease duration and specific taste modalities remains incompletely characterized. <b>Aim:</b> This study aimed to (i) compare orosensory detection thresholds for lipid and sweet tastes between patients with recent type 2 diabetes mellitus (rT2DM) (duration ≤ 5 years) and chronic type 2 diabetes mellitus (cT2DM) (duration > 5 years), and (ii) determine whether diabetes duration is associated with alterations in chemosensory function in a North African population. <b>Methods:</b> A cross-sectional comparative pilot study was conducted at the National Institute of Nutrition and Food Technology in Tunis, Tunisia, from April to June 2021. Sixty-seven patients with type 2 diabetes mellitus (T2DM) receiving oral antidiabetic medication were recruited through systematic sampling and divided into two groups: rT2DM (<i>n</i> = 30, duration ≤ 5 years) and cT2DM (<i>n</i> = 37, duration > 5 years). Orosensory detection thresholds for lipid taste were assessed using eight ascending concentrations of linoleic acid ranging from 0.018 to 12 mmol/L. In contrast, sweet taste thresholds were evaluated using a sucrose concentration series ranging from 0.01 to 5 mmol/L. The three-alternative forced-choice method with an ascending-concentration presentation was employed for both taste modalities. Detection thresholds were defined as the lowest concentration at which participants correctly identified the taste quality. <b>Results:</b> Patients with cT2DM exhibited significantly elevated orosensory detection thresholds compared to those with rT2DM for both taste modalities tested. The median linoleic acid detection threshold was 6.000 mmol/L in cT2DM versus 0.058 mmol/L in rT2DM (<i>p</i> < 0.001), representing a 107-fold increase in detection threshold. For sweet taste, the median sucrose detection threshold was 1.0 mmol/L in cT2DM compared with 0.5 mmol/L in rT2DM (<i>p</i> < 0.001), indicating a 2-fold increase in the threshold. In the overall patient cohort, the duration of diabetes was positively correlated with both fat taste perception thresholds (r = 0.657, <i>p</i> < 0.001) and sweet taste perception thresholds (r = 0.466, <i>p</i> < 0.001). However, when analyses were performed by diabetes duration-based subgroups, these correlations were observed only for fat taste perception in cT2DM, with no statistically significant correlations found in rT2DM. In multivariate linear regression analyses adjusted for age, body mass index, and sex/gender, the duration of diabetes remained independently associated with fat and sweet taste perception. <b>Conclusions:</b> Extended T2DM duration is associated with substantial elevations in orosensory detection thresholds for both lipid and sweet tastes in a North African population. These findings suggest that disease chronicity may contribute to chemosensory impairment, potentially influencing dietary preferences and metabolic control in patients with diabetes.