A retrospective study of 210 cases of diabetes was carried out at King Khalid University Hospital diabetes clinic to delineate etiologic factors in non-insulin dependent diabetes mellitus (NIDDM). Standardised detailed questionnaires were administered to both cases and controls and the information sought included general demographics, dietary patterns, anthropometric values, family history, consanguinity and familial aggregation of Diabetes Mellitus (DM). Familial aggregation yielded an odds ratio of 6:2 which suggests a causal association with DM. A synergistic effect of familial aggregation was observed which needs to be further explored in future studies.