Background: Type 2 diabetes mellitus TDM) is a global pandemic and the highest beden is projected to be in Middle Eastern countries including Oman Prediabetes is a Lyperglycaemic state that carries a high risk for progression to T2DM. In Oman. prediabetic individuals constitute for 36.1% of the achile Omani population Globally, merous researches documented that lifestyle intervention (diet and playsical exercise) was effective in preventing T2DM among prediabetic individuals. In Oman and other Arab countries; however, there is death of research assessing the effect size of lifestyle intervention on preventing the progression from prediabetes to T2DM Aim: This study aims to assess the effect of lifestyle intervention (diet and playsical exercise counselling) on reducing the incidence of T2DM among adult prediabetic individuals in primary health care setup. Methods: A retrospective cohort study was conchucted on 1026 Omani adults with prediabetes who attended 24 primary health care facilities in Muscat Governorate Data were collected from a prediabetes register over five-year period from Jamuary 2014 to December 2018. Data covered socio-demographic, anthropometric and clinical information over study period. Lifestyle intervention included dietary and playsical excercise counseling and monitoring standardized sessions. Exposure to lifestyle intervention was categorized into optimal (received 5-6 monthly sessions), sub-optimal (received 24 monthly sessions) and unexposed (received 1 session). The primary outcome was progression to T2DM Person-time was calculated as person-mouths, and measures of Occurence calculated were incidence proportion and incidence rate Incidence rate ratio (IRR) was calculated as a measure of association and effect size of exposure on reduction of T2DM OCCwrence Data were analyzed using survival analysis modeling, Kaplan-Meier curves and Cox proportional hazards (Cox PH) modeling Results: Overall, 1026 participants (362 men and 664 women), were included in the study. Categories of exposure to life intervention were as follows: 521 (50.8%) were espored, while 505 (49.2%) were exposed of the exposed individuals, 441 (87.3%) received suboptimal exposure while the remaining 64 (12.8%) received optimal eposure. At baseline and compared to men Women had higher proportion of obesity but lower proportion of co-morbidities such as hypertension and dyslipidemin. By the ead of follow up, a total of 24,995 person-months were incuted, of which 9,215 person months among men while 15,780 were among women A total of 76 (7.4%) participants progressed to T2DM of whom 23 (6.4%) were men while 53 (8.0%) were women Therefore, the overall Incidence rate of T2DM was 3.04 per 1000 per month with 2.50 in men conpared to 3.36 in women. Overall the incidence rate increased as the ape of participants increased. Results showed significant reduction in weight, BMI and waist circumference with the increase in exposure sessions. Results of incidence rate of T2DM showed that over 5-year period incidence rate ratio (IRR) was higher for individuals with exposed (combined: sub-optimal & optimal) compared to exposed group (1.21, 95% CI (0.8, 2.0) and suboptimal exposure compared to exposed group (1.28, 95% a (0.8, 2.0). After adjustment for confounders, Cox PH model revealed that the adjusted IRR was [1.10, 95% CI (0.7, 1.75)] in exposed (combined) . exposed and [1.16, 95% CI (0.75, 1.85)] in sub-optimal exposure vs. exposed Lower risk of progression to T2DM was observed among optimal exposure your compared to exposed as RR. [0.7, 95% CI (0.21, 23)] and remained the same after statistical adjustment with Cox PH model Conclusion: This study provides supportive evidence that lifestyle intervention counselling hand the potential to reduce the occurrence of T2DM provided that is offered optimally, ie for at least six months with a frequency of obe session per month The effect of lifestyle intervention counselling on reducing the CCTeace of TDM was found to be more profound among women compared to men.