Hypertension in type 2 diabetes mellitus in Isfahan, Iran: Incidence and risk factors

Abstract

Background: Evidence on the long-term incidence of and risk factors of hypertension in diabetic patients is scarce and mainly derived from studies in developed countries. Evidence from developing countries is required for planning a well-co-ordinated approach to this public health problem in these countries. Objective: The objectives of present study were to estimate the incidence of and risk factors for the development of hypertension in people with type 2 diabetes mellitus using routinely collected data from a clinical information system at Isfahan Endocrinology and Metabolism Research Centre, Iran. Method: During the mean (standard deviation (S.D.)) follow-up period of 2.9 (2.5) (range 1–11) years, 3202 diabetic patients (1315 male and 1887 female) from Isfahan Endocrinology and Metabolism Research Centre out patient clinics, Iran have been examined. The mean (S.D.) age of participants was 48.3 (10.6) years with a mean (S.D.) duration of diabetes of 6.5 (6.7) years at initial registration. Blood pressure was measured by standardised protocols, and hypertension was defined as at least in two consecutive measurements within 2 months a systolic and/or diastolic blood pressure of ≥130 and/or ≥80 mmHg and/or taking anti-hypertensive medication. Results: Among the 3202 patients free of hypertension at initial registration who attended the clinic at least twice in the period 1992–2004, the incidence of hypertension was 20.8 (20.6 male and 20.9 female)) per 100 person-years based on 9403 person-years of follow-up. The age-adjusted incidence rate of hypertension was 22% lower among insulin-treated than non-insulin-treated type 2 diabetes mellitus clinic attenders and it was greater with older age. Using a Cox's Proportional Hazards Model, male gender, and treatment regimen were significant independent predictors of hypertension. Smoking, duration of diabetes, age at diagnosis of diabetes, fasting blood glucose, glycosylated haemoglobin, BMI, proteinuria and creatinine, had no significant independent association with hypertension when other covariates were considered. Conclusion: These findings will help the identification of those patients at particular risk of hypertension and strongly support the case for vigorous control of blood pressure on type 2 diabetic patients.