OBJECTIVES: The aim of this study is to assess the impact of Ramadan intermittent fasting on glycemic control in individuals diagnosed with type 2 diabetes. METHODS: This historical prospective study utilized electronic health records from a major state-mandated healthcare provider. The research sample included Muslim adults aged 40-70 years, who had been diagnosed with type 2 diabetes. Their place of residence, categorized as a yes/no predominantly Muslim-Arab city, was identified for analysis purposes. Data regarding fasting plasma glucose and HbA1C levels were extracted from the 90 days preceding and the 45 days following the Ramadan period, spanning across six years (2011-2016). The annual data were aggregated and analyzed using a mixed-model ANOVA. RESULTS: Muslim participants during Ramadan were found to have a higher likelihood of experiencing a change in HbA1C levels of ≥ 0.5 % compared to their non-Muslim counterparts, displaying an odds ratio (OR) of 1.89 (95 % confidence interval [CI]: 1.24-2.88). Among Muslims with initially normal HbA1C levels (≤7 %), there was a heightened risk of both decreased (≤-0.5 %) HbA1C levels (OR=2.62, 95 % CI: 1.15-6.00) and increased (≥+0.5 %) HbA1C levels (OR=2.85, 95 % CI: 1.24-6.57) in comparison to the non-Muslim group. CONCLUSIONS: In Muslims with type 2 diabetes, fasting during the Ramadan increases the risk of their HbA1C-levels rising by more than 0.5 %. These results underscore the potentially dual impact of Ramadan intermittent fasting on glycemic control in individuals with type 2 diabetes.