People with type 2 diabetes have different levels of natural antimicrobial proteins in their saliva. Diabetes lowers the defensins (hBD‑1, hBD‑2, hBD‑3) but raises cathelicidin (LL‑37), especially when gum disease is also present. These changes are linked to blood sugar levels (HbA1c) and gum inflammation.

<b>Objective:</b> Type 2 diabetes mellitus (T2DM) is a well-defined risk factor of periodontitis and it can affect expression of human beta-defensins (hBDs) and cathelicidin (LL-37) as well. The aim of the present study was to evaluate the impact of periodontitis and T2DM on salivary concentrations of these antimicrobial peptides.<b>Material and methods:</b> Unstimulated saliva samples, together with full-mouth periodontal recordings were collected from 92 individuals with periodontitis (63 with T2DM and 21 smokers) and 86 periodontally healthy controls (58 with T2DM and 21 smokers). Salivary hBD-1, -2, -3, LL-37, and advanced glycalization end products (AGE) concentrations were measured by enzyme-linked immunosorbent assay.<b>Results:</b> Among the periodontitis patients, T2DM group demonstrated lower levels of hBD-1 (<i>p</i>&#x2009;=&#x2009;.006), hBD-2 (<i>p</i>&#x2009;&lt;&#x2009;.001) and hBD-3 (<i>p</i>&#x2009;&lt;&#x2009;.001), and higher levels of LL-37 (<i>p</i>&#x2009;&lt;&#x2009;.001) compared to systemically healthy controls. When only periodontally healthy controls were included into the analysis, higher hBD-1 (<i>p</i>&#x2009;=&#x2009;.002) and LL-37 (<i>p</i>&#x2009;&lt;&#x2009;.001) levels were found in T2DM patients in comparison to systemically healthy controls. Salivary LL-37 levels were associated with HbA1c and periodontitis, while hBD-2, hBD-3 and levels associated only with HbA1c.<b>Conclusion:</b> In the limits of this study, hyperglycaemia can be proposed as a regulator of salivary hBD and cathelicidin levels. Periodontitis, on the other hand, affects only salivary LL-37 levels.