Objective: To evaluate serum calcium and phosphate levels in Pre-diabetic, Diabetic & non-diabetic subjects. Material and Methods: This comparative cross-sectional study was conducted at the Department of Chemical Pathology and Endocrinology, Armed Forces Institute of Pathology, from July to December 2021. The study used a non-probability consecutive sample to include 300 people. Those people have been divided into three groups; diabetics, pre-diabetics and non-diabetics with a hundred people in every group. Blood specimens had been taken for the estimation of calcium, phosphate, HbA1c, plasma glucose and insulin in fasting in their respective tubes. SPSS version 24 was used to inspect the data. All descriptive variables had their means and standard deviations calculated. To examine descriptive characteristics within and between all groups, one way ANOVA and post hoc LSD were performed, and p-values 0. 05 were considered significant. Results: Calcium and Phosphorus levels were lower in Diabetic group (Ca= 1.97±0.16mmol/l, PO4 = 0.76±0.07 mmol/l) as compared to pre-diabetic group (Ca= 2.15±0.18 mmol/l, PO4 = 0.93±0.06 mmol/l) and higher in non-diabetic group (Ca= 2.33±0.10mmol/l, PO4 = 1.19±0.20 mmol/l) than both other groups. A one-way ANOVA and Post Hoc LSD revealed that the difference between and within groups was statistically significant with a p value of 0.01. Conclusion: Our research has shown that as glycemic control slowly deteriorates, blood calcium and phosphate levels fall. Keywords: Calcium, Phosphorus, Pre-diabetes, Type 2 diabetes mellitus.