Background: The aim of the study was to value the behaviour of systolic (S) and diastolic (D) arterial pressure (AP)/24 hrs in a group of diabetic patients insulin-dependent (IDDM) and non insulin-dependent (NIDDM) with preserved renal function.
Methods: We examined 65 diabetic patients (aged 39.1 +/- 23.3), 33 IDDM (aged 18.2 +/- 7.5; years of diabetes: 5.8 +/- 4.9) and 32 NIDDM (aged 60.7 +/- 11.4; years of diabetes: 7.2 +/- 7.5). In all of them we computed BMI and determined creatinine clearance, glycosylated haemoglobin A, total and HDL-associated cholesterol, triglyceridemia, middle glycemia and microalbuminuria. AP measurement was performed by 24 hrs monitoring (periodicity 15') using a Takeda 2420 measurer. Chronobiological characteristics of AP were analysed by statistical method of cosinor according to Halberg, examining if there was or not a blood pressure circadian rhythm (PCR) (p < 0.05) and its characteristics represented by the mesor, the amplitude and the acrophase. Moreover the patients were subjected to a diet with fixed contents of sodium (130 mEq/day) and afterwards we drew (every 4 hours) renin (R), aldosterone (A1) and atrial natriuretic factor (ANF) which were analysed with cosinor's method. The purpose was not to compare the two populations, not homogeneous between them and not different only for the years of diabetes, but to study their blood pressure behaviour, the rhythm, the order of the indicated hormones for possible pathogenetic connections.
Results: NIDDM presented higher blood pressure values (PAS 134.2 +/- 3.5 and PAD 80.9 +/- 2 mmHg) than IDDM (PAS 116.6 +/- 1 and PAD 66.4 +/- 1.7 mmHg), still in limits of substantial normality. The acrophase was in the midday for NIDDM (PAS 11:25', PAD 12:06') and in the early afternoon for IDDM (PAS 14:15', PAD 14:06'). Analysing the trend of the AP in the single cases, PCR was present in 70% and absent in 30% of IDDM while it was persistent in 56% and disappeared in 44% of NIDDM. IDDM without PCR differed from those with it in years of diabetes (p < 0.001), body weight (p < 0.02), BMI (p < 0.01), triglyceridemia (p < 0.05), all more elevated, as well as in higher PAS and PAD (p < 0.001) and in higher concentration of ANF (p < 0.05). The same comparison was done in NIDDM. Patients without PCR were older (p < 0.025), had higher PAS (p < 0.025) and PAD (p < 0.001) and also a more activated ANF (p < 0.001).
Conclusions: This hormonal anomaly may be ascribed to a lower excretion of sodium with consequent expansion of extracellular volume due to antinatriuretic action of insulin often found at high plasmatic levels particularly in NIDDM.