Blood pressure and cardiac autonomic function in relation to risk factors and treatment perspectives in Type 1 diabetes

"Arterial stiffness is not associated with changes in the circadian pattern of blood pressure in patients with type 1 diabetes mellitus and cardiovascular autonomic dysfunction"

INTRODUCTION

Cardiovascular autonomic neuropathy (CAN) associates an abnormal circadian pattern in blood pressure (BP) regulation that might be aggravated by the coexistence of arterial stiffness. We aimed to evaluate the effect of arterial stiffness in the circadian rhythm of BP in patients with type 1 diabetes and CAN.

METHODS

Cross-sectional study including 56 consecutive patients with type 1 diabetes and CAN, with (n = 28) or without (n = 24) arterial stiffness as defined by an ankle-brachial index above 1.2. CAN was diagnosed by BP and heart rate responses to active standing and cardiovascular autonomic reflex tests. Absence of nocturnal decrease in BP-"non-dipping" pattern- was defined by a daytime to nighttime decrease in mean BP smaller than 10%.

RESULTS

The study's subjects mean age was 40 ± 11 years-old, their mean duration of diabetes was 22 ± 10 years, and their mean A_1c was 7.9 ± 1.5%. A "non-dipping" pattern was observed in 28 patients (54%) regardless of the presence or absence of arterial stiffness. Age, waist circumference, body mass index, and A_1c, were introduced as independent variables into a multiple regression analysis. The stepwise model (R²: 0.113, p = 0.016) retained only A_1c levels (β: ‒ 0.333, 95% confidence interval [CI]: -3.10 to -0.33) as significant predictor of the percentage of nighttime decrease in mean BP.

CONCLUSIONS

A non-dipping pattern in BP is very common in patients with type 1 diabetes presenting with subclinical CAN and is associated with a poorer metabolic control. On the contrary, coexistence of arterial stiffness is not associated with abnormalities in circadian BP regulation.

Disruption of circadian blood pressure, heart rate and the impact on glycemic control in type 1 diabetes

Patients with type 1 diabetes (DM-1) have an increased mortality and morbidity risk compared to non-diabetic subjects. Even not recognized clinically at the early period of disease; patients with DM-1 show subtle neurological and cardiovascular abnormalities which is partly responsible for the increased mortality. One of these abnormalities is the disruption of circadian rhythms. Various factors such as autonomic dysfunction, sleep disturbance, smoking, cardiac and kidney function, atherosclerosis, arterial stiffness are suggested to cause these disturbances. Additionally these abnormalities have also implications regarding target organ damage such as microalbuminuria, retinopathy, and structural changes in glomeruli. Surprisingly, there are scarce data regarding the effect of tight blood glucose control and insulin on circadian rhythms in patients with DM-1. By the light of aforementioned data this review will try to summarize causes and consequences of disruption of circadian rhythms and the impact on glycemic control on these issues in patients with DM-1.

Cardiac autonomic neuropathy and early progressive renal decline in patients with nonmacroalbuminuric type 1 diabetes

BACKGROUND AND OBJECTIVES

Cardiac autonomic neuropathy predicts future adverse renal outcomes in the general population. This study sought to determine its relationship with early progressive renal decline in type 1 diabetes.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A subset of participants with normoalbuminuria (n=204) or microalbuminuria (n=166) from the First Joslin Kidney Study underwent assessment for cardiac autonomic neuropathy using heart rate variability during baseline visits performed from January 1991 to April 1992. Cardiac autonomic neuropathy was defined as an R-R variation (mean circular resultant) <20. Participants also had baseline and follow-up measurement of eGFR. Early progressive renal decline was evaluated according to two definitions: early GFR loss (slope of eGFR estimated by cystatin C <-3.3%/year) and incident advanced CKD (stage ≥3, defined by eGFR [calculated by Modification of Diet in Renal Disease method] <60 ml/min per 1.73 m(2)). Association with baseline cardiac autonomic neuropathy was assessed by adjusted logistic regression and Cox proportional hazards.

RESULTS

Among the 370 participants, 47 (13%) had baseline cardiac autonomic neuropathy, 51 (14%) had early GFR loss, and 68 (18%) had incident advanced CKD over a median 14-year follow-up. Early GFR loss occurred in 15 (32%) of the 47 patients with baseline autonomic neuropathy and in 32 (10%) of the 323 without baseline autonomic neuropathy (P<0.001). Baseline autonomic neuropathy was strongly associated with odds of early GFR loss (adjusted odds ratio, 4.09; 95% confidence interval, 1.65 to 10.12; P=0.002). Incident advanced CKD was observed in 22 (47%) of those with baseline autonomic neuropathy and 46 (14%) of those without baseline autonomic neuropathy (P<0.001). Autonomic neuropathy was independently associated with incident advanced CKD (adjusted hazard ratio, 2.76; 95% confidence interval, 1.44 to 5.30; P=0.002).

CONCLUSIONS

Cardiac autonomic neuropathy was a strong independent predictor of the long-term risk of early progressive renal decline in type 1 diabetes. Future research should explore the mechanisms by which autonomic neuropathy may be associated with renal function loss.

Longitudinal trends in use and costs of prescription medication in patients with type 1 diabetes: the impact of renal disease

OBJECTIVE

We estimated trends in prescription medication costs in out-patients with type 1 diabetes by various stages of diabetic nephropathy (DN), before the development of end-stage renal disease, between 1995 and 2005.

METHODS

Patients with normo- (n = 1,334), micro- (n = 206), and macroalbuminuria (n = 365) were identified from the Finnish Diabetic Nephropathy (FinnDiane) database. All purchases of medications were obtained from the Drug Prescription Register.

RESULTS

The costs levels differed significantly (P < 0.0001) between all groups. The estimated annual costs per patient in 1995 were €1,310 (95% CI 1,230-1,400), €1,450 (1,300-1,600), and €1,770 (1,620-1,930) in the normo-, micro-, and macroalbuminuria groups, respectively. The corresponding costs in 2005 were €1,950 (1,830-2,080), €2,110 (1,910-2,320), and €2,900 (2,650-3,180). The costs increased in all groups over time (P < 0.0001). The annual average increase was 3.5%, 3.3%, and 5.2% in each group. After the generic substitution was introduced, the costs of agents acting on the renin- angiotensin system and lipid-modifying agents dropped, although the number of users increased at the same time.

CONCLUSIONS

More severe stages of DN have a substantial impact on the costs, which suggests that early prevention and intensive treatment of renal disease may generate remarkable annual cost savings.

Urinary biomarkers involved in type 2 diabetes: a review

Diabetes mellitus is one of the most challenging health concerns of the 21st century. With at least 30% of the diabetic population remaining undiagnosed, effective and early diagnosis is of critical concern. Development of a diagnostic test, more convenient and reliable than those currently used, would therefore be highly beneficial. Urine as a diagnostic medium allows for non-invasive detection of biomarkers, including some associated with type 2 diabetes and its complications. This review provides a synopsis of those urinary biomarkers that potentially may provide a basis for the development of improved diagnostic tests. Three main pathways for the sourcing of potential makers are identified: kidney damage, oxidative stress and low-grade inflammation including atherosclerosis/vascular damage. This review briefly presents each pathway and some of the most relevant urinary biomarkers that may be used to monitor the development or progression of diabetes and its complications. In particular, biomarkers of renal dysfunction such as transferrin, type IV collagen and N-acetyl-beta-D-glucosaminidase might prove to be more sensitive than urinary albumin, the current gold standard, in the detection of incipient nephropathy and risk assessment of cardiovascular disease. Inflammatory markers including orosomucoid, tumour necrosis factor-alpha, transforming growth factor-beta, vascular endothelial growth factor and monocyte chemoattractant protein-1, as well as oxidative stress markers such as 8-hydroxy-2'deoxyguanosine may also be useful biomarkers for diagnosis or monitoring of diabetic complications, particularly kidney disease. However, the sensitivity of these markers compared with albumin requires further investigation.

Clinical Use and Pathogenetic Basis of Laboratory Tests for the Evaluation of Primary Arterial Hypertension

This review focuses on the laboratory biochemical tests that are useful in the diagnostic approach to the hypertensive patient. A "minimal" diagnostic laboratory work-up, including a small number of tests that are simple and relatively inexpensive, is first described. Because these tests provide basic information on the presence of major cardiovascular (CV) risk factors and target organ damage, and might give some clues to the presence of a secondary form of hypertension (HT), they should be performed on all patients presenting with HT. Other tests that are aimed at assessing the overall CV risk, a major determinant of prognosis that dictates the therapeutic strategy in the individual HT patient, are then discussed. They allow identification of major CV risk factors and associated clinical conditions which, if present, lead to a substantial change of therapeutic strategy. The role of C-reactive protein as a marker of atherosclerosis and its predictive value for CV events are also discussed. Finally, a section is devoted to tests that are currently confined to research purposes, such as markers of endothelial function including endothelin-1, homocysteine and genetic analysis.

Nondipping and its relation to glomerulopathy and hyperfiltration in adolescents with type 1 diabetes

OBJECTIVE

To determine whether there is a relation between dipping/nondipping status and end-organ damage (measured as renal glomerulopathy) and long-term renal function in order to predict the development of nephropathy in normoalbuminuric patients with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Analysis of renal biopsy and ambulatory blood pressure measurements was done in relation to renal function tests performed during a 10-year period. Forty unselected patients (16 girls), with a mean age of 17.7 years and a mean duration of 10.7 years, were studied. The renal biopsies were examined by electron microscopy. Ambulatory blood pressure was monitored (Space Labs 90 207). Systolic nondippers were defined as a <7%, diastolic nondippers as a <14%, and mean arterial blood pressure (MAP) nondippers as a <12% fall in blood pressure during the night. Renal function was evaluated every other year by clearances of inulin (glomerular filtration rate [GFR]) and para-amino hippurate (effective renal plasma flow [ERPF]), and filtration fraction (GFR/ERPF) was calculated. Overnight urinary albumin excretion rate and long-term mean HbA(1c) were measured.

RESULTS

MAP (27% of the patients) and diastolic nondippers (12%) had a significantly thicker basement membrane; larger mesangial matrix volume fraction; and higher long-term GFR, nighttime heart rate, and mean HbA(1c) than dippers.

CONCLUSIONS

Nondipping status was related to more renal morphological changes and long-term hyperfiltration in normoalbuminuric adolescents and young adults, despite a short duration of type 1 diabetes. Nondipping status may be an early predictor of later nephropathy.