Background: Progressive residual alveolar ridge resorption is one of the main causes of loss of stability and retention of complete denture. The severity of bone loss is a serious clinical condition facing the aging population. Resorption of residual alveolar bone is further accelerated by uncontrolled diabetes. So the present study was conducted to compare the bone heights of residual alveolar bone in edentulous patients between diabetes and non- diabetes and also to correlate with the HbA1C level of diabetes. Materials and Methods: 25 Apparently healthy (non-diabetic) and 25 diabetic edentulous age and sex matched subjects were recruited in the present study with a mean age of 61-65 years. Resorption of the maxillary and mandibular residual alveolar ridges were assessed in digital panoramic radiographs. Measurements were performed using Romexis software. The amount of resorption was calculated and correlated to gender, age and duration of edentulousness. Statistical analysis was performed using SPSS (V17.0). Level of significance was set at 0.05. Results: Our results showed that residual ridge resorption was higher in females (52%) when compared to males (48%). Diabetics had significantly (p<0.05) more residual alveolar bone resorption in right and left Mandibular premolar, Maxillary premolar and molar regions. There was no significant difference (p<0.05) in Gonial angle between the groups. A significant correlation was found between HbA1C level and residual ridge resorption. A weak positive correlation (r=+1) was observed between duration of edentulism and resorption of residual alveolar ridge. Conclusion: Completely edentulous, women in particular, are at more risk to have ridge resorption than non-diabetic subjects. Reduced mandibular height is directly related to years of edentulousness with greater amount of resorption among diabetics.