Covid-19 has impacted millions of people and may disproportionately affect those with hypertension and diabetes. Due to inadequate methods in published systematic reviews, the prevalence of diabetes and hypertension and associated risks of poor outcomes in Covid-19 patients are unknown. We searched, databases from December 1, 2019 to April 6, 2020 and selected observational peer-reviewed studies in English language of patients with Covid-19. Independent reviewers extracted data on study participants, interventions, and outcomes and assessed risk of bias, and the certainty of evidence using the. We included 65 (15,794 participants) observational studies at moderate-to-high risk of bias. Overall prevalence of diabetes and hypertension was 12% (95% CI 10-15%, n=12870, I2: 89%), and 17% (95% CI 13-22%, n=12709, I2: 95%), respectively. In severe Covid-19, the prevalence of diabetes and hypertension were 18% (95% CI 16-20%, n=1099, I2: 0%) and 32% (95% CI 16-54%, n=1078, I2: 63%), respectively. Unadjusted relative risk for ICU admission and mortality were 1.96 (95% CI 1.19-3.22, n=8,890, I2: 80%, p=.008) and 2.78 (95% CI 1.39-5.58, n=2058, I2: 75%, p=.0004) for diabetics; and 2.95 (95% CI 2.18-3.99, n=1737, I2: 0%, p<.001) and 2.39 (95% CI 1.54-3.73, n=3107, I2: 66%, p<.001) for hypertensives. Neither diabetes (1.50, 95% CI 0.90-2.50, n=1991, I2: 74%, p=.119) nor hypertension (1.48, 95% CI 0.99-2.23, n=2023, I2: 69%, p=.058) was associated with severe Covid-19. In conclusion, the risk of ICU admission and mortality for patients with diabetes or hypertension who developed Covid-19 is increased compared to those without these comorbidities.