The diagnostic performance of copeptin in clinical practice: A prospective study.

OBJECTIVE: Plasma copeptin is a relatively new biomarker for evaluation of arginine vasopressin (AVP) secretion. The aim of this study was to test the diagnostic performance of copeptin in patients with polyuria-polydipsia syndrome. DESIGN, PATIENTS AND MEASUREMENTS: This was a prospective study where 88 patients with polyuria-polydipsia syndrome were evaluated with a water deprivation test (WDT). Weight, urine osmolality, urine specific gravity, and plasma copeptin were collected at baseline, after 8 h, and at termination of the WDT when one of the following had been reached: (i) >3% weight reduction, (ii) urine specific gravity >1.017 or urine osmolality >600 mOsm/kg, or (iii) intolerable adverse symptoms. RESULTS: Of 88 patients (57 women), 21 (24%) were diagnosed with central diabetes insipidus (cDI), 5 (6%) with nephrogenic DI (nDI), and 62 (71%) with primary polydipsia (PP). Median (interquartile range) copeptin at baseline was 1.7 (1.4-2.5) pmol/L in cDI, 22 (18-65) pmol/L in nDI, and 2.7 (2-4) pmol/L in PP. After 8 h of WDT, the highest copeptin in patients with cDI was 4.0 pmol/L. In patients with PP: (i) 41 had urine osmolality <600 mOsm/kg, 7 (17%) of these had copeptin >4.0 pmol/L, (ii) 21 had urine osmolality ≥600 mOsm/kg, 14 (67%) of these had copeptin >4.0 pmol/L. CONCLUSIONS: Copeptin >4.0 pmol/L after an overnight WDT can be used to rule out cDI and copeptin ≥21 pmol/L at baseline to diagnose nDI. The diagnostic performance of copeptin in the context of the WDT is otherwise limited in the diagnostic work-up of patients with polyuria-polydipsia syndrome.

Ghrelin Levels in Basal Conditions and During Glucose Tolerance Test in Prediabetic and Diabetic Patients.

Ghrelin is associated with glucose homeostasis but its' possible relevance with glucose levels in physiological and pathological conditions has so far been poorly investigated. The aim of the present study was to evaluate circulating ghrelin levels in prediabetic and diabetic patients in basal conditions and in response to oral glucose tolerance test (OGTT). A total of 90 male adults aged 40 - 73 years old were enrolled in our study. Fasting and postprandial plasma ghrelin, insulin and glucose levels were measured at 0, 60, 120 and 180 min following an OGTT in 40 patients with type 2 diabetes mellitus (T2DM), 20 with impaired glucose tolerance (IGT) and 30 controls. Incremental and total area under response curve were determined and calculated for glucose, insulin and ghrelin. Fasting plasma ghrelin concentrations were significantly lower in the T2DM group than IGT and control group patients (p<0.01) but not between healthy subjects and IGT group (p=0.746). In the diabetics' group ghrelin levels showed a statistically significant negative correlation with insulin and a positive correlation with HbA1c and glucose. At all time points after the OGTT ghrelin concentrations were significantly lower in the T2DM group compared to IGT group and controls. Plasma ghrelin concentrations are lower in male diabetic patients at the fasting state and remain lower at all time points after an OGTT while minor differences were found between normal and IGT subjects. Ghrelin might play a role in insulin and glucose metabolism in diabetic patients but not in patients with IGT.

The influence of insulin-induced hypoglycemia on copeptin concentrations.

Plasma copeptin is a biomarker that reflects arginine vasopressin (AVP) secretion. In this study we measured copeptin during insulin tolerance test (ITT) in 65 patients referred to our department for evaluation of anterior pituitary function. Plasma for measurements of copeptin were collected at the start of the test and regurarly up to 120 minutes thereafter. Of 60 patients who developed significant hypoglycemia and were included in the analyses, 13 (22%) had corticotropic deficiency, 11 (18%) had thyreotropic deficiency, 33 (55%) had growth hormone deficiency and 4 (6%) had AVP deficieny (AVPD). Thirty-seven (62%) patients had at least one anterior pituitary deficiency. In patients without AVPD, median (range) copeptin increased from 4.5 pmol/L (1.3-33.0) to a maximum of 6.2 pmol/L (2.0-34.4; p<0.001). Baseline copeptin was similar in men and women, but maximal copeptin during ITT was higher in men. Copeptin concentrations were not affected by age, BMI, somatotropic, or corticotropic function. Copeptin concentrations were lower in patients with AVPD than patiets without AVPD, and in patients with thyrotropic deficiency, compared to patients with intact thyrotropic function, both at baseline and during ITT. In conclusion, copeptin increases significantly during insulin induced hypoglycemia but is of limited value in predicting anterior pituitary hormonal function.

Glycaemic control and incidence of heart failure in 20,985 patients with type 1 diabetes: an observational study.

BACKGROUND: Poor glycaemic control is associated with microvascular and macrovascular complications in type 1 diabetes, but whether glycaemic control is associated with heart failure in such patients is not known. We aimed to assess this association in a large cohort of patients with type 1 diabetes identified from the Swedish national diabetes registry. METHODS: We identified all patients (aged ≥18 years) with type 1 diabetes and no known heart failure who were registered in the national diabetes registry between January, 1998, and December, 2003. These patients were followed up until hospital admission for heart failure, death, or end of follow-up on Dec 31, 2009. We calculated incidence categorised by glycated haemoglobin A(1c) (HbA(1c)) values, and we assessed the association between patients' characteristics, including HbA(1c), and heart failure. FINDINGS: In a cohort of 20,985 patients with mean age of 38·6 years (SD 13·3) at baseline, 635 patients (3%) were admitted to hospital with a primary or secondary diagnosis of heart failure during a median follow-up of 9·0 years (IQR 7·3-11·0), with an incidence of 3·38 events per 1000 patient-years (95% CI 3·12-3·65). Incidence increased monotonically with HbA(1c), with a range of 1·42-5·20 per 1000 patient-years between patients in the lowest (<6·5%) and highest (≥10·5%) categories of HbA(1c). In a Cox regression analysis, with adjustment for age, sex, duration of diabetes, cardiovascular risk factors, and baseline or intervening acute myocardial infarction and other comorbidities, the hazard ratio for development of heart failure was 3·98 (95% CI 2·23-7·14) in patients with HbA(1c) of 10·5% or higher compared with a reference group of patients with HbA(1c) of less than 6·5%. Risk of heart failure increased with age and duration of diabetes. Other modifiable factors associated with increased risk of heart failure were smoking, high systolic blood pressure, and raised body-mass index. In a subgroup of 18,281 patients (87%) with data for blood lipids, higher HDL cholesterol was associated with lower risk of heart failure, but there was no association with LDL cholesterol. INTERPRETATION: The positive association between HbA(1c) and risk of heart failure in fairly young patients with type 1 diabetes indicates a potential for prevention of heart failure with improved glycaemic control. FUNDING: AstraZeneca, Novo Nordisk Scandinavia, Swedish Heart and Lung Foundation, and Swedish Research Council.