Altered circadian blood pressure rhythm and progression of diabetic nephropathy in non-insulin dependent diabetes mellitus subjects: an average three year follow-up study.

BACKGROUND

In addition to autonomic dysfunction, diabetic nephropathy has been identified as another factor inducing a reversed circadian blood pressure (BP) rhythm in diabetic subjects. This study was carried out to assess the relationship between alterations in circadian BP rhythm and progression of diabetic nephropathy in subjects with non-insulin dependent diabetes mellitus (NIDDM).

METHODS

Ambulatory 24-hour BP, 24-hour urinary albumin excretion rate (UAE), and plasma hormonal factors were measured during an average 3-year follow-up in 16 hospitalized subjects with NIDDM. Twelve age-matched control subjects were also studied.

RESULTS

During an average 3-year follow-up, diabetic subjects had no significant progression of severe nephropathy and/or somatic neuropathy and showed no transition from a normal to a reversed mean blood pressure (mBP) pattern. However, mBP during whole day or nighttime, but not daytime, at baseline in diabetic subjects was high as compared with control subjects exhibiting an increased night/day mBP ratio and a decreased night/day mBP difference. The mBPs during various time periods (whole day, daytime, and nighttime) at follow-up in diabetic subjects were more elevated than those at baseline, showing a more increased night/day mBP ratio and a more decreased night/day mBP difference. In diabetic subjects, UAE during follow-up was increased, and UAE increments were well correlated with changes in mBP during whole day and nighttime. Plasma renin activity (PRA) and plasma aldosterone (PA) were decreased, while plasma alpha-atrial natriuretic peptide (ANP) was increased at follow-up, compared with at baseline. The mBP increments during various time periods were well correlated with changes in these hormonal factors, and UAE increments were well correlated with changes in PA and plasma ANP.

CONCLUSIONS

The altered circadian BP rhythm observed in diabetic subjects may occur at the early stage of diabetic nephropathy with opposite changes in plasma renin-aldosterone and plasma ANP.