Dissertation (MSc Pediatric Nursing)Background: The caregivers’ level of knowledge on T1DM plays a major role in the management of affected children. However, limited studies have evaluated the knowledge of caregivers on type one diabetes mellitus. The objective of this study was to assess the effect of caregivers’ level of knowledge on blood glucose control in children with type one diabetes mellitus in Zanzibar. Methods: A cross- sectional study was carried out at the diabetic clinics hospitals in Zanzibar. A convenient sampling technique was used to select 134 children and used to collect data from caregivers. Caregivers’ knowledge on T1DM was measured by Michigan Diabetes Research and Training Centre, blood Pressure and blood glucose control, was measured by CDiC case record form. The data were processed and analyzed by SPSS version 20. Results: Sixty seven percent (67.2%) of caregivers had a good knowledge (AOR=0.278, P=0.0049) and 32.8% poor knowledge. Prevalence of complications which were developed by children was loss of vision 38.1%, numbness 30.6%, and chronic ulcers 18.7%, lower limb swelling 9% and constipation 2.2%. Out of the 134 children, 66 (49.3%) had hyperglycemia and 68 (50.7%) had a normal blood sugar level. The risk of having hyperglycemia was significantly lower among children whose caregivers had a good knowledge on T1DM (AOR=0.356, P=0.0192). Furthermore, almost 25% of the children had a high blood pressure and 75 % normal blood pressure (AOR=0.176, P=0.0002). Conclusion: This study has found out that, majority of caregivers had a good knowledge on type one diabetes mellitus and it was also found that, old age and higher education were factors which were significantly associated with levels of knowledge of caregivers. Furthermore children with T1DM, employed and higher education were observed and found to have associated with good control of blood glucose and blood pressure.