Blood pressure (BP) control of type 2 diabetic subjects aged under 65 years was assessed in a primary care setting. In addition, the usefulness of 24-h ambulatory BP measurement (ABPM) in the treatment of hypertension was assessed in subjects with diastolic BP (DBP) > or = 90 mm Hg. Of the total 381 diabetic subjects, 260 (68%) participated in the first phase, and 48 of the 110 subjects with DBP > or = 90 mm Hg were equipped with a Meditech ABPM-02 monitor in the second phase. The mean BP of the 260 participants was 156/91 (s.d. 22/11) mm Hg. According to the WHO criteria, 58% had hypertension, and 42% had a diagnosis of hypertension. Albuminuria > or = 20 micrograms/min was detected in 32% of the subjects. Ten percent of the subjects with diagnosed hypertension had a mean BP < 140/90 mm Hg and 50% had a mean BP > or = 160/95 mm Hg, as many as 38% of those not having a diagnosis of hypertension. Only long-term poor BP control in casual measurements was associated with albuminuria (42% vs 27%, P = 0.018). It is concluded that BP control was unsatisfactory and diagnosis of hypertension was delayed in most subjects with type 2 diabetes. Occurrence of microalbuminuria was associated with poor BP control and urinary albumin excretion rate may be useful in assessing the BP control. Further studies are needed to assess the position of 24-h ABPM in the treatment of hypertension of subjects with type 2 diabetes.