Prevalence of Type 2 Diabetes Among Patients with Hypertension Under the Care of 30 Italian Clinics of Hypertension: Results of the (Iper)tensione and (dia)bete Study

Background And Purpose: Hypertension is known to be highly prevalent among patients with diabetes and associated with an increased risk of cardiovascular damage. In contrast, relatively few investigations have addressed the prevalence of diabetes among patients with hypertension. The purpose of the present study was to examine the prevalence of type 2 diabetes, the effectiveness of hypertension and diabetes control and the association with other cardiovascular risk factors and previous cardiovascular diseases in a cohort of patients with hypertension referred to 30 hospital outpatient clinics for the treatment of hypertension.

Methods And Patients: Patients were considered as having diabetes if they were already on an antidiabetic treatment either with diet or medications. All other patients had fasting plasma glucose measured on two separate occasions and were classified as having diabetes if both values were at least 140 mg/dl (7.8 mmol/l) and as not having diabetes if both values were less than 110 mg/dl (6.1 mmol/l). In patients with a single determination of at least 110 mg/dl, the final diagnosis of diabetes was established according to the result of an oral glucose tolerance test. A secondary definition of diabetes was also used, that is two fasting plasma glucose values of at least 126 mg/dl (7.0 mmol/l). In all patients, serum total, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol, fasting serum triglycerides, serum creatinine and urinary albumin were also evaluated.

Results And Conclusion: Among the 1397 recruited patients, 242 (17.3%) were diagnosed as having diabetes according to the primary definition and 244 (17.5%) according to the secondary definition. In 195 out of the 242 (14%), the diagnosis was already known whereas, in the remaining 47 (3.3%), it was made de novo. In 61.4% of those already having diabetes, plasma glucose was at least 140 mg/dl (7.8 mmol/l), whereas only in 8.4% of them was it less than 110 mg/dl (6.1 mmol/l). Patients with diabetes were older, heavier and with a greater familiar predisposition. Patients with diabetes had higher values of systolic blood pressure than individuals without diabetes (150 +/- 17 vs. 144 +/- 16 mmHg, respectively; P < 0.001), lower high-density lipoprotein cholesterol and higher triglycerides and microalbuminuria. Overall, among patients with hypertension and diabetes, only 3% had blood pressure and HbA1c within the recommended limits. The prevalence of previous cardiovascular disorders was two to three times higher than among individuals without diabetes.