Biomedical subjects
Publications and source records attributed to U Adamson.
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OBJECTIVE: A number of short-term studies using the continuous glucose monitoring system (CGMS) indicate that improved metabolic control can be observed in patients with type 1 diabetes when CGMS is applied in clinical practice. Data have also accumulated to suggest that spot measurements of glucose performed four times a day would not detect as much as 70% of all hypoglycaemic episodes registered by CGMS. When more frequent reference values were obtained however it was inferred that nighttime hypoglycaemia reported by CGMS may be spurious. As most assessments with CGMS have been utilizing abdominal subcutaneous tissue, we were interested to evaluate whether differences between blood glucose and sensor readings obtained from different sites exist. RESEARCH DESIGN AND METHODS: Two viscometric affinity glucose sensors, applicable to subcutaneous tissue of both forearm and abdomen, were inserted subcutaneously in 12 non-diabetic subjects. Sensors generated glucose data at 3 min intervals and venous blood glucose was determined in duplicates by HemoCue at 15-90 min intervals for 24 hours. Each subject consumed three carbohydrate-rich meals, performed an exercise test, and was observed during nocturnal bed-rest at the research center. RESULTS: The initial decrease of blood glucose during exercise was not fully detected by the sensors. Otherwise, no significant differences between sensor values and blood glucose were observed during day-time. During nocturnal bed-rest abdominal sensor values came approximately 20% lower than blood glucose (P<0.001) and forearm sensor readings. CONCLUSION: It is concluded that a difference between glucose values obtained from abdominal and forearm subcutaneous fat can be observed during nocturnal bed-rest in non-diabetics.
OBJECTIVE: To evaluate the accuracy of nocturnal continuous glucose monitoring by CGMS. RESEARCH DESIGN AND METHODS: A CGMS was inserted in 14 type 2 diabetic patients on combined oral and insulin therapy at altogether 15 occasions. During the second (48 hours) and third (72 hours) night of registration each subject was observed and plasma glucose was analysed seven times during the night by venous sampling and compared to CGMS. These venous values were not used for calibration of the sensor. Pairs of data were analysed using correlation coefficient, Bland-Altman graphs and Clarke Error Grid analysis. RESULTS: 32% of CGMS data did not meet the quality criteria for optimal accuracy and were excluded. A correlation coefficient of 0.80 (p < 0.0001) was seen after 48 hours and a lower coefficient of 0.33 (p = 0.0082) after 72 hours. Bland-Altman analyses demonstrated that the dispersion of the values around the mean of differences was wider after 72 hours as compared to after 48 hours. In the Clark Error Grid analysis 100% of data were within zones A and B after 48 hours, with 60% in zone A. After 72 hours only 44% were in zone A and 7% of data were in the clinically unacceptable zone D. CONCLUSION: The MiniMed Medtronic CGMS has acceptable nocturnal accuracy after 48 hours of registration, but the accuracy thereafter deteriorates with time, implicating that the CGMS thereafter may prove less useful for nocturnal monitoring.
AIMS: To study the prevalence of severe hypoglycaemia (SH) in relation to risk factors in Type 1 diabetic (T1 DM) patients over a period of 14 years. METHODS: We performed a cross-sectional survey of a cohort of 178 T1 DM patients registered at our out-patient clinic in 1984 to be repeated in 1998. An identical questionnaire was sent to the patients in the beginning of 1985 and 1999, respectively, regarding the problem of SH in the preceding year. Additional clinical data were obtained from the patients' medical records on insulin treatment, long-term complications, morbidity, and co-medication. RESULTS: At follow up, the use of multiple insulin injection therapy had increased from 71% to 98% (P < 0.001) and daily self-monitoring of blood glucose (SMBG) from 17% to 48% (P < 0.001). Twenty-seven percent were treated with direct-acting insulin analogues in 1998. An increasing number of patients reported unawareness of hypoglycaemia, 54% vs. 40% (P < 0.01), and nocturnal events were more frequent, 83% vs. 76% (P < 0.05). The prevalence of SH had increased from 17% to 27% (P < 0.05) and a slight decrease of HbA1c, 7.6% to 7.4% (P < 0.05) was documented. CONCLUSION: We conclude that despite more frequent use of multiple injection therapy and SMBG, the prevalence of SH has increased by > 50% over 14 years. A multiple logistic regression analysis of risk factors for SH explained less than 10% of the variance, implicating only unawareness of hypoglycaemia and HbA1c.
Previous studies have shown that the relationship between gastrointestinal symptoms and gastric emptying is weak. Therefore the quantitative assessment of gastric emptying with a relatively simple, non-invasive test would be of considerable clinical value in insulin-treated diabetic patients to identify those with disturbed gastric emptying. The aim of this investigation was to evaluate the inter- and intra-subject variability of a paracetamol-pasta test in healthy subjects and in IDDM patients. Eighteen healthy subjects (8 women) with a mean age of 37 years (range 19-68) and 19 IDDM patients (10 women) with a mean age of 48 years (range 25-62) and mean duration of diabetes of 28 years (range 6-52) were studied on two occasions with an interval of 1 to 4 weeks. After an overnight fast the subjects ingested a standardized pasta meal mixed with 2 g paracetamol in a period of 15 min. Blood samples were drawn at regular intervals after meal intake and analysed for paracetamol (P) and blood glucose. The serum levels of P were significantly lower at 15 min in diabetic patients. The intra-subject coefficients of variation (CV%) of the areas under the serum paracetamol concentration-time curve (AUC) were almost identical in healthy and diabetic subjects, while the intra-subject CV of the P-Tmax was considerably lower in diabetic patients as well as markedly lower than the corresponding inter-subject CV. The inter-subject CVs of all parameters calculated were generally higher in diabetic patients. This study indicates that the assessment of paracetamol absorption kinetics during a paracetamol-pasta test is reproducible in healthy as well as in diabetic subjects. Diabetic patients with non-optimal glucose control and without a case history indicating gastroduodenal motor function disturbances achieve lower serum concentration of P at 15 min and generally display a higher inter-individual variability indicative of subclinical disturbances of gastric emptying in this group of patients.
OBJECTIVE: Our aim was to distinguish beneficial effects of B-cell rest from other effects of correction of hyperglycaemia. For this purpose we used diazoxide which reversibly blocks insulin secretion. MATERIAL AND METHODS: Eight obese (age 53 +/- 1 yr: BMI 33 +/- 2 kg/m2: 4 females) type 2 diabetic patients with poor metabolic control (HbA1c 8.7 +/- 0.9% ref.<5.2%) were studied twice after a randomly ordered treatment period of five days of intensive i.v. insulin treatment alone or i.v. insulin with peroral diazoxide (300 mg/day, divided into 3 doses). The glycaemic control was not altered between the two treatment periods. Insulin secretion was measured in response to i.v. glucose and arginine. RESULTS: Insulin infusion was used to achieve close to identical degrees of glycaemia during the two treatment periods. Previous treatment with diazoxide was associated with a moderate 1.9 +/- 0.6 fold rise in insulin response to intravenous glucose (p=0.04) and 1.6 +/- 0.4 fold increased glucose potentiation of arginine-induced insulin secretion (GPAIS) (p=0.04). Conversely, after insulin alone there was no response to i.v. glucose and no change in GPAIS. CONCLUSIONS: Short-term diazoxide treatment improved important parameters of B-cell function and these effects could be dissociated from confounding effects of changes in glycaemia. Consequently, the results indicate beneficial effects of B-cell rest.
We conducted a long-term clinical follow-up of 20 insulin-treated diabetic patients with the problem of repeated severe hypoglycaemic events, identified during 1982-1984. Furthermore, we investigated the reproducibility of a standardized insulin-infusion test among eight of these patients and 10 insulin-dependent diabetes mellitus patients without the problem of severe hypoglycaemia. At start of the follow-up, the patients were characterized, which revealed that proposed risk factors for severe hypoglycaemia were very common and that at least one predisposing factor was present in all patients. No fatal episode of hypoglycaemia occurred in this group of patients during the follow-up. Emergency visits due to hypoglycaemia decreased during the follow-up from 1.05 year(-1) in 1982-1984 to 0.42 year(-1) in 1992-1994 (P=0.024). No association to HbAlc was seen (P=0.11). A correlation with the change to multiple insulin regimen was seen with a incidence of 1.27 year(-1) before the change to 0.47 year(-1) after (P=0.003). The glucose response to an insulin-infusion test appeared reproducible among the patients with recurrent attacks of severe hypoglycaemia.
OBJECTIVES: To study effects of insulin-induced hypoglycaemia on the cardiac repolarization, using QT interval measurements, in patients with type 2 diabetes. DESIGN: Hypoglycaemia was induced by an i.v. insulin-infusion and blood glucose was clamped at 2.7 mmol L-1 for 60 min (T = 90-150 min) in two experiments, with (+GLIB) and without (-GLIB) glibenclamide. In a third experiment, with similar hyperinsulinaemia, glucose was clamped at a euglycaemic level (;5 mmol L-1). ECG was continuously recorded for arrhythmia-monitoring, and 12-lead ECGs were recorded at T = 0 and 150 min. QT intervals were measured, and we determined QT dispersion (difference between the maximum and the minimum QT interval) reflecting interlead variability of repolarization. SUBJECTS: Thirteen patients with type 2 diabetes, on combined insulin and glibenclamide treatment, were studied during hypoglycaemia, and eight of them participated in the euglycaemic experiment. RESULTS: No significant arrhythmias were seen during hypoglycaemia but the mean QT intervals and QT dispersion increased significantly (P < 0.001), with no differences between -GLIB and +GLIB. During the euglycaemic clamp all QT measurements remained unchanged. Serum potassium decreased significantly (P < 0.001) during all three clamps, but the decrease was more pronounced during hypoglycaemia. The change in potassium was not correlated to the degree of QT prolongation or QT dispersion. CONCLUSIONS: Significant changes in the repolarization of the heart can be seen during hypoglycaemia in patients with type 2 diabetes, indicating an increased risk of arrhythmia at low blood glucose levels.
AIM: To explore whether the lowering of insulin relates to changes in leptin following weight reduction after vertical banded gastroplasty (VBG) in seven grossly obese women (BMI 45.9 +/- 1.5 kg/m2). RESULTS: At 6-24 months after VBG, BMI was reduced to 31.3 +/- 0.9 kg/m2 (p < 0.018), leptin from 43 +/- 9 to 12 +/- 2 ng/ml (p < 0.018) and insulin from 172 +/- 19 to 71 +/- 2 pmol/l (p=0.018). The reduction in leptin correlated to the reduction in insulin (r = 0.94, p = 0.002) but not to that of BMI (r = 0.05, NS). CONCLUSION: Reduction in insulin seems more important for reduction in leptin than lowering of BMI, suggesting a close association between leptin and insulin in obese subjects.
OBJECTIVE: The aim of this study was to determine whether variations in the blood glucose concentration within the normal postprandial range affect the gastrokinetic action of erythromycin. METHODS: Six healthy male volunteers, aged 20-33 yr underwent measurements of gastric emptying on 2 separate days; blood glucose concentrations were maintained at approximately 4 mmol/L (72 mg/dl) on 1 day and at 8 mmol/L (144 mg/dl) on the other. The order of the two studies was randomized and they were separated by 4-7 days. On both days, erythromycin (3 mg/kg) was administered intravenously over 15 min immediately before consumption of 300 g minced beef labeled with 20 MBq 99mTc-sulphur colloid chicken liver and 150 ml water labeled with 67Ga-EDTA. RESULTS: Gastric emptying of solid (p < 0.05) and liquid (p < 0.0001) were slower at a blood glucose concentration of 8 mmol/L (144 mg/dl) when compared to 4 mmol/L (72 mg/dl). The slowing of gastric emptying was associated with greater retention of both solid and liquid in the proximal (p < 0.06) and distal (p < 0.01) stomach. CONCLUSIONS: After administration of erythromycin, gastric emptying and intragastric distribution of solids and liquids is influenced by physiological changes in the blood glucose concentration.
Intensifying pharmacological therapy in patients with type 2 diabetes increases the risk of hypoglycemia and often requires the simultaneous use of more than one agent. Combining insulin and sulfonylurea is an effective and frequently used therapy in such patients. However, sulfonylurea derivatives have been shown to affect the release of glucagon, indicating a possible effect of such therapy on hormonal counterregulation to hypoglycemia. Thirteen patients receiving combined therapy were studied on two occasions: 1) after a wash-out period of glibenclamide (-GLIB), and 2) after resuming combined treatment for 6 months (+GLIB). We performed nonstep-wise, hyperinsulinemic hypoglycemic clamps using a constant i.v. insulin infusion and clamping blood glucose at 2.7 mmol/L (48 mg/dL) for 60 min. C Peptide levels were significantly higher during + GLIB, but no significant differences were seen in peripheral plasma insulin levels (+GLIB mean +/- SD, 70 +/- 17 mU/L vs. -GLIB, 75 +/- 14; P = 0.26). Epinephrine responses were similar in the two tests, but when glibenclamide was present the glucagon response was smaller, both the peak value (P = 0.016) and the incremental area under the curve (P = 0.011) as well as the total area under the curve (P = 0.016). These results suggest that intraislet insulin secretion is of importance for the alpha-cell responsiveness to hypoglycemia in these patients.
BACKGROUND: The objective was to elicit whether hormonal responses to and subjective symptoms of hypoglycemia are modified during pregnancy in patients with insulin-dependent diabetes mellitus. METHODS: In ten type I diabetic women, hyperinsulinemic hypoglycemic clamps, with target arterial blood glucose content of 2.2 mmol/l, were performed during the third trimester of pregnancy and 5-13 months after delivery. The levels of arterial glucose and venous catecholamines, pituitary growth hormone, cortisol, glucagon, dehydroepiandrosterone and free insulin were assessed repeatedly. Subjective symptoms of hypoglycemia were recorded on a visual analog scale. The paired t-test and Wilcoxon signed rank test were used for statistical comparisons. RESULTS: Adrenaline and dehydroepiandrosterone increased during hypoglycemia on both occasions, but dehydroepiandrosterone disclosed a significantly different pattern of response during pregnancy (p=0.016). The cortisol increase was augmented during pregnancy (420+/-50 vs. 310+/-30 nmol/l non-pregnant, p=0.039), while the increase in pituitary growth hormone (hGH) was diminished (5.4+/-1.2 vs. 27.9+/-5.4 microg/l non-pregnant, p=0.001), but nevertheless the increase during pregnancy was significant (p=0.002). Three of the eight subjective symptoms of hypoglycemia recorded were less prominent during pregnancy, namely 'inability to concentrate' (p=0.03), 'headache' (p=0.01) and 'pounding heart' (p=0.03). CONCLUSIONS: Albeit some subjective symptoms were diminished during pregnancy, the study gives no evidence that, in diabetic patients, pregnancy per se impairs the counterregulatory response to hypoglycemia, with the exception of growth hormone. However, despite the suppressed basal growth hormone secretion in late pregnancy, the study disclosed a secretory response of this hormone at hypoglycemia.
Recent studies indicate that C-peptide, when given to patients with insulin-dependent (Type 1) diabetes mellitus (IDDM), exerts significant effects on microvascular and neuronal functions. Adjuvant therapy with C-peptide has been advocated in the treatment of IDDM patients. Since endogenous insulin secretion is believed to be of importance for the alpha-cell function, we addressed the issue whether C-peptide given acutely interferes with the responses to hypoglycaemia. Seven IDDM patients were randomly exposed to hypoglycaemia with and without exogenous C-peptide. Insulin and and C-peptide were given intravenously in equimolar amounts for 3 hours. The decrease of blood glucose was faster and more pronounced during C-peptide infusion, yielding a significantly lower AUC 0-180 min of blood glucose (38.5 +/- 1.6 vs 44.4 +/- 2.2 mmol l(-1)h(-1); p = 0.032). No difference between the two experiments was found concerning glucagon when the AUC, delta-values or levels at separate points of time were calculated. In conclusion, the main finding of this study was that exogenous C-peptide, given acutely, gave rise to a more rapid onset of hypoglycaemia yielding no detectable differences with respect to the response of glucagon and other counterregulatory hormones.
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A method to monitor glucose in whole blood is presented. The aim of the project was to develop a prototype for a bedside monitor system for semi-continuous monitoring of the blood glucose concentration, requiring only one calibration. This was made possible by using the special advantage of the thermal sensor technique in combination with the adjustment of flow. The glucose concentration was determined from the difference between the sensor response and an estimated background signal. Using standard addition technique, calibration factors for background and sensitivity were set and remained unchanged during the monitoring. The background signal was 45 +/- 8 mV (mean +/- S.D., n = 8) and the sensitivity was 28 +/- 1 mV/mmol (mean +/- S.D., n = 4). Recovery in whole blood was 90-98% (mean 94%, n = 12). With an injection interval of 3 min the precision with the sensor was < 3% over more than 100 blood samples. Response time was about 60 s. The calculated glucose values correlated, r = 0.98, with the values obtained with an YSI glucose analyser (Yellow Springs Instruments. Yellow Springs, OH, USA), over the range 2-20 mmol/l.
The aim of the present study was to evaluate the effect of the alpha 2-adrenoceptor antagonist idazoxan on hormonal responses and hypoglycaemia symptoms in patients with insulin-dependent (Type 1) diabetes mellitus. Six male Type 1 diabetic patients were studied with and without intravenous infusion of idazoxan. Hypoglycaemia was induced by an intravenous infusion of insulin (100 mU.kg-1.h-1), together with a glucose clamp, to obtain an arterialised venous blood glucose level of 2.3 mmol/l. Idazoxan was given at a dose of 295 micrograms/kg. Venous blood samples were obtained for analyses of free insulin, growth hormone (GH), glucagon and catecholamines. Symptoms were scored on a visual-analogue rating scale. Areas under the curves with and without idazoxan were respectively 22.4 +/- 7.0 vs 33.0 +/- 9.6 micrograms.l-1.h (p = 0.17) for GH, 4.1 +/- 1.1 vs 2.4 +/- 0.9 nmol.l-1h (p < 0.05) for adrenaline, 5.6 +/- 0.9 vs 1.3 +/- 0.5 nmol.l-1.h (p < 0.05) for noradrenaline and 51 +/- 38 vs -40 +/- 11 ng.l-1.h (p < 0.05) for glucagon. Sweating and palpitations were more pronounced during idazoxan infusion than during the control test. It is concluded that idazoxan increases catecholamine and glucagon responses as well as some of the warning signals of hypoglycaemia in Type 1 diabetic patients, whereas the GH response seems less affected by idazoxan.
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