Independent association between type 2 diabetes mellitus and hypertension over a period of 10 years in a large inpatient population

Diabetes mellitus (DM) and hypertension (HTN) are common risk factors for heart disease in the population. The goal of this study was to evaluate independent association between type 2 DM and HTN using a very large database. We used ICD-9 codes for type 2 DM (250.00, 250.02) and HTN (401.0, 401.1, 401.9) from the Nationwide Inpatient Sample (NIS) database. We randomly selected the years in the database between 1992 and 2002. We used uni- and multi-variate analysis to evaluate any association between type 2 DM and HTN adjusting for co-morbid conditions. The 1992 database contained a total of 6,195,744 patients. Type 2 DM was associated with 37.5% of patients with HTN vs. 11.4% of the control group (odds ratio (OR): 4.63, Confidence interval (CI) 4.61-4.693, p < 0.001). The 2002 database contained a total of 7,853,982 patients. Type 2 DM was associated with 57.2% of patients with HTN vs. 22.9 of the control group (OR: 4.49, CI 4.47-4.52, p < 0.001). Using multivariate analysis adjusting for age, gender, hyperlipidemia, obesity, smoking, and chronic renal failure, type 2 DM remained independently associated with HTN in both years (for the year 1992: OR: 2.49, CI: 2.47-2.51, p < 0.001 and for the year 2002 OR: 2.19, CI: 2.18-2.20, p < 0.001). The same association was persistently found using samples for each year between 1992 and 2002. The presence of type 2 DM is strongly associated with HTN. This association is independent of co-morbid conditions and was persistent with similar odds ratio over a period of 10 years.