Background: Insulin sensitivity impairment and beta-cell function defects are involved in type 2 diabetes and other metabolic diseases. Objective: This study aimed to estimate the range of insulin sensitivity and beta-cell function among healthy Vietnamese adults. Methods: The data were collected from 51 healthy adults (17 men, 34 women; mean age 26.7 ± 4.7 years). All participants were free from diabetes, other major diseases, and associated risk factors. All participants had a normal fasting plasma glucose level, BMI, serum insulin and lipid levels, oral glucose tolerance test results, waist circumference, and family history. Beta-cell function and insulin sensitivity were calculated using the HOMA2 Calculator version 2.2. Results: The beta-cell function, insulin sensitivity, and insulin resistance indices were 90.1 ± 21.7, 178.4 ± 58.9, and 0.63 ± 0.20, respectively, for both plasma glucose and insulin concentrations and 237.6 ± 44.8, 41.3 ± 8.7, and 2.53 ± 0.53, respectively, for both plasma glucose and C-peptide concentrations. Beta-cell function was lower in men than in women (p < 0.05). Beta cell function showed a significant inverse correlation with insulin sensitivity. The total/HDL cholesterol ratio was significantly inversely correlated with insulin sensitivity and significantly directly correlated with insulin resistance. However, no significant correlations were found between beta cell function; insulin sensitivity; the insulin resistance index; or total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), or high-density lipoprotein cholesterol (HDL-C) among healthy Vietnamese adults. Conclusions: In healthy Vietnamese adults, insulin sensitivity was strongly correlated with beta cell function and high-density lipoprotein cholesterol (HDL-C) levels. This study provides important insights into the normal range of insulin sensitivity and beta-cell function among healthy Vietnamese adults.