Ambulatory blood pressure monitoring (ABPM) in normotensive adolescents with type 1 diabetes

Factors influencing blood pressure and microalbuminuria in children with type 1 diabetes mellitus: salt or sugar?

BACKGROUND

The aim of the study is to identify the effect of salt intake and diabetes itself on blood pressure (BP) profile and microalbuminuria in children with type one diabetes mellitus (T1DM). Our hypothesis is that higher amount of salt consumption and/or hyperglycemia may impair blood pressure pattern in children with T1DM.

METHODS

This cross-sectional study included 84 children and adolescents with T1DM (62% females, age 13.9 ± 3.2 years, disease duration 7.3 ± 3.1 years, 43% poorly controlled diabetes) and 54 aged- and sex-matched healthy children with an adequately collected 24-h urine samples. Urine sodium, creatinine, and microalbumin were measured and salt intake was assessed on the basis of sodium excretion in 24-h urine. Blood pressure profile of the children with T1DM was evaluated with 24-h ambulatory blood pressure monitoring.

RESULTS

Compared to the children with well-controlled diabetes, children with poorly controlled diabetes had significantly higher standard deviation scores (SDS) of nighttime systolic BP (0.22 ± 1.28 vs - 0.87 ± 0.76, p = 0.003) and lower dipping in diastole (13.4 ± 5.9 vs 18.4 ± 8.1, p = 0.046). Among T1DM group, children with the highest quartile of salt intake had higher nighttime systolic and diastolic BP-SDS (0.53 ± 1.25 vs - 0.55 ± 0.73, p = 0.002 and 0.89 ± 1.19 vs 0.25 ± 0.63, p = 0.038, respectively) and lower dipping in systole compared to their counterparts (7.7 ± 5.0 vs 11.5 ± 6.1, p = 0.040). High averaged HbA1c was independently associated with higher both daytime and nighttime systolic BP-SDS (p = 0.010, p < 0.001) and nighttime diastolic BP-SDS (p = 0.001), and lower diastolic dipping (p = 0.001). High salt intake was independently associated with higher nighttime systolic BP-SDS (p = 0.002) and lower systolic dipping (p = 0.019). A 24-h MAP-SDS was the only independent risk factor for microalbuminuria (p = 0.035).

CONCLUSION

Beside poor diabetic control, high salt consumption appears to be an important modifiable risk factor for impaired BP pattern, which contributes to the development of diabetic kidney disease in children with T1DM.

Microalbuminuria in relation to metabolic control and blood pressure in adolescents with type 1 diabetes

INTRODUCTION

The objective of this study was to assess the frequency of microalbuminuria and the relationship with other risk factors for the development of diabetic nephropathy.

MATERIAL AND METHODS

Our cross-section study involved a group of 60 adolescence of both sexes, mean age 15.3 ±2.43 years with mean duration of diabetes 7.74 ±3.44 years. Albumin excretion rate was measured on 2-3 samples of the first morning urine in the period below 6 months and persistent microalbuminuria was defined if its increased in two out of three urine specimens. Ambulatory blood pressure was monitored (ABPM, SpaceLabs 90207).

RESULTS

Microalbuminuria developed in 13.3% of adolescents with mostly completed sexual development, statistically significantly poorer metabolic control (9.79% vs. 8.7%) and higher BMI (23.59 kg/m(2) vs. 20.85 kg/m(2)) than in the patients with normoalbuminuria. The mean night-time systolic blood pressure (SBP) was statistically significantly higher in microalbuminuric patients than in normoalbuminurics. The nocturnal dip was reduced in 41.7% of our patients; 38.5% of nondippers were in normoalbuminuric and 62.5% in microalbuminuric patients.

CONCLUSIONS

Diabetic adolescents require particular attention in order to minimize the factors such as high HbA(1c), elevated body mass index and night-time SBP in the development of incipient nephropathy.

Superior consistency of ambulatory blood pressure monitoring in children: implications for clinical trials

BACKGROUND

Casual office blood pressure (CBP) measurements are still standard in antihypertensive drug trials. In pediatric hypertensive trials, ethical considerations, very low disease prevalence and the marked impact of white-coat hypertension create the need for very sensitive and reproducible techniques of BP assessment. We hypothesized that ambulatory BP monitoring (ABPM) may identify treatment effects more sensitively than CBP and thereby reduce sample sizes required in pediatric antihypertensive trials.

METHODS

Standard deviations (SDs) were used to assess population variability of CBP and ABPM at baseline and after 6 months standardized antihypertensive treatment from a trial investigating the BP-lowering effect of ramipril in children with chronic kidney disease.

RESULTS

In 157 hypertensive children, ramipril had a similar mean BP-lowering effect on clinic and ambulatory 24-h BP for systolic (-10 vs. -11 mmHg, P = NS) and diastolic values (-9 vs. -11 mmHg, P = NS). However, the SDs of the CBP responses were up to 39% larger than those of ABPM (SBP 15.5 vs. 9.4; DBP 13.8 vs. 8.8; both P < 0.0001). Using power analysis, we demonstrate that, depending on the magnitude of the expected antihypertensive effect and trial design, the utilization of ABPM in antihypertensive drug efficacy studies allows reduction of sample sizes by 57-75%. This reduction of cohort size with ABPM is substantially greater than previously observed for adults.

CONCLUSION

The primary use of ABPM can substantially reduce the number of children put at potential risk in blinded antihypertensive drug trials by up to three quarters.

Diabetic nephropathy in children and adolescents

Type 1 diabetes mellitus (T1DM) commonly occurs in childhood or adolescence, although the rising prevalence of type 2 diabetes mellitus (T2DM) in these age groups is now being seen worldwide. Diabetic nephropathy (DN) develops in 15-20% of subjects with T1DM and in similar or higher percentage of T2DM patients, causing increased morbidity and premature mortality. Although overt DN or kidney failure caused by either type of diabetes are very uncommon during childhood or adolescence, diabetic kidney disease in susceptible patients almost certainly begins soon after disease onset and may accelerate during adolescence, leading to microalbuminuria or incipient DN. Therefore, all diabetics warrant ongoing assessment of kidney function and screening for the earliest manifestations of renal injury. Pediatric health care professionals ought to understand about risk factors, strategy for prevention, method for screening, and treatment of early DN. This review considers each form of diabetes separately, including natural history, risk factors for development, screening for early manifestations, and strategy recommended for prevention and treatment of DN in children and adolescents.