To study the incidence of glucose intolerance in CP patients without diabetes by performing oral glucose tolerance test (OGTT). We screened consecutive Indian CP patients without diabetes over 6 months by performing OGTT and correlated with physical characteristics and glycated hemoglobin (HbA1c). We also compared c-peptide and pancreatic polypeptide response in different groups based on OGTT. Relevant statistical tests were performed. P < 0.05 was considered significant. Total of 171 patients were screened. Mean duration of CP was 5.03 ± 4.32 years. 55 were detected to have prediabetes and 40 DM on OGTT. CP patients with diabetes and prediabetes had significantly dilated pancreatic duct compared to non-diabetic CP (4.2 ± 2.7 mm, 3.6 ± 2.7 mm, 2.84 ± 2.25 mm; p = 0.018). Fasting blood glucose (FBS) and 2-hour OGTT were 109.35 ± 19.06, 97.47 ± 11.94, 85.24 ± 9.95 and 236.13 ± 31.42, 154.65 ± 19.53, 112.89 ± 16.32 in patients with DM, prediabetes and CP patients without diabetes (p < 0.0001). There was a good c-peptide response (p = 0.001) and reduced pancreatic polypeptide response (p = 0.003) in CP patients compared to controls. Early in the course of disease reduced pancreatic polypeptide response in the presence of good c-peptide response may result in development of DM.