Insulin Resistance in Type 2 Diabetes with Periodontal Disease and Comparison of Various Surrogate Markers: HOMA IR,HOMA IR Using C peptide,and Triglyceride Glucose Index

Abstract

Background and Aims:

(a) To evaluate insulin resistance (IR) in individuals with Type 2 Diabetes Mellitus (T2DM) and periodontal disease (PD) in a local South Indian population. (b) To study the correlation between surrogate markers of IR—namely HOMA-IR (using insulin), HOMA-IR (using C-peptide), and Triglyceride-Glucose Index (TGI).

Materials and Methods:

This is a cross-sectional study conducted at Indra Diabetes Centre, Tuticorin, Tamil Nadu. A total of 145 T2DM patients aged 30–85 years were screened for PD and enrolled. A control group of 145 age-matched, non-diabetic genetic relatives of the T2DM group was also screened and recruited similarly. PD severity was classified into four stages by the dentist, as per the Periodontitis Consensus Report 2017. The demographic details, namely age, gender, as well as BMI and fasting blood samples for Glucose, Insulin, C-peptide, Triglycerides, and HbA1c, were collected from T2DM (D) and non-diabetic control (ND) participants enrolled on the study.

IR was estimated using three methods: HOMA-IR (insulin-based, HOMA-IRi), HOMA-IR (C-peptide-based, HOMA-IRc), and TGI. Statistical analysis was performed using JASP software. IR levels were compared between the D and ND groups. Subgroup analyses by gender and PD stage were also performed. Then, correlation analyses of the IR of HOMA IRc and TGI with HOMA IRi were conducted.

Results:

Using a regional HOMA-IRi cut-off of 1.23, IR was observed in both diabetic and non-diabetic groups, with significantly higher values in the diabetic group. No significant differences in IR were found between genders or across the various stages of PD in either group. HOMA-IRc and TGI showed a strong positive correlation with the standard HOMA-IRi method.

Conclusions:

(a) IR was observed in both diabetic and non-diabetic groups with PD; however, it was significantly higher in the diabetic group. There was no significant difference in IR between genders or among the four stages of PD in either group. PD appears to aggravate IR in diabetic individuals and may contribute to the development of IR in non-diabetics, potentially increasing their risk of developing diabetes. (b) Since HOMA-IR using C-peptide correlates well with the standard insulin-based HOMA-IR, it may be preferred for research or clinical use in laboratories where maintaining an ideal cold chain is challenging, which is an important consideration in the Indian setting. (c) As lipid profiles are routinely performed in primary care for all diabetic patients, the TGI can be easily calculated and included in laboratory reports. It is simple, cost-effective, and widely accessible, and may assist clinicians in identifying IR and selecting appropriate therapeutic strategies.