Background and objective: Subjects with diabetes mellitus (DM) are at high risk of cardiovascular events. However, their cardiovascular risk varies according to several clinical characteristics like age, sex, ethnicity, type and duration of the DM, quality of glycemic control, type of hypoglycemic treatment, or the presence of nephropathy or previous cardiovascular events. It is not known if these characteristics have been sufficiently reported in clinical trials on hypertension including subjects with DM.
Material and method: We analyzed randomized controlled clinical trials about treatment of hypertension published before May 2003 with the following characteristics: a) inclusion of subjects with DM and b) a primary end-point including at least one of the following events: myocardial infarction, cerebrovascular disease or total mortality. In these trials we evaluated the above-mentioned clinical characteristics concerning cardiovascular risk.
Results: Sixteen trials were eventually analyzed. These trials were classified into: a) trials designed only for subjects with DM (RENAAL, UKPDS 38, UKPDS 39, IDNT); b) trials with a subgroup analysis for subjects with DM (SHEP, Syst-Eur, MICRO-HOPE, HOT, STOP-2, LIFE), and c) trials without a subgroup analysis for subjects with DM (CAPP, NORDIL, INSIGHT, ALLHAT, SANBPSG, CONVINCE). All these trials included a total of 33984 subjects with DM, most of them > or = 55 years old. The percentage of women evaluated ranged from 33.5 to 71.9% although in 2 trials no data were found regarding this percentage (12.5%). There was no information on ethnicity in 10 trials (62.5%), on the type of DM in 7 (43.8%), on the duration of the disease in 13 (81.3%), on the degree of glycemic control in 10 (62.5%), on the type of hypoglycemic treatment in 11 (68.8%), on the presence or absence of nephropathy in 11 (68.8%) and on the presence or absence of previous cardiovascular events in 3 (18.8%). Trials without subgroup analysis for subjects with DM had a lower reporting of the clinical characteristics of the subjects evaluated than the rest of the trials.
Conclusions: The reporting of relevant clinical characteristics of cardiovascular risk in subjects with DM in the main clinical trials on hypertension is low, diminishing their external validity. To optimize the therapeutic recommendations in the treatment of hypertension in DM these deficiencies should be overcome.