Improved glycaemic control with insulin glargine plus insulin lispro: a multicentre, randomized, cross-over trial in people with Type 1 diabetes

AIMS

To compare blood glucose control using insulin glargine + insulin lispro with that on NPH insulin + unmodified human insulin in adults with Type 1 diabetes managed with a multiple injection regimen.

METHODS

In this 32-week, five-centre, two-way cross-over study, people with Type 1 diabetes (n = 56, baseline HbA1c 8.0 +/- 0.8%) were randomized to evening insulin glargine + mealtime insulin lispro or to NPH insulin (once- or twice-daily) + mealtime unmodified human insulin. Each 16-week period concluded with a 24-h inpatient plasma glucose profile.

RESULTS

HbA1c was lower with glargine + lispro than with NPH + human insulin [7.5 vs. 8.0%, difference -0.5 (95% CI -0.7, -0.3) %, P < 0.001]. This was confirmed by an 8% lower 24-h plasma glucose area under the curve (AUC) (187 vs. 203 mmol l(-1) h(-1), P = 0.037), a 24% reduction in plasma glucose AUC > 7.0 mmol/l1 (47 vs. 62 mmol l(-1) h(-1), P = 0.017) and a 15% lower post-prandial plasma glucose AUC (75 vs. 88 mmol l(-1) h(-1), P = 0.002). There was no reduction in night-time plasma glucose AUC or increase in plasma glucose area < 3.5 mmol/l. Monthly rate of nocturnal hypoglycaemia was reduced by 44% with glargine + lispro (0.66 vs. 1.18 episodes/month, P < 0.001).

CONCLUSIONS

Compared with NPH insulin + unmodified human insulin, the combination of insulin glargine with a rapid-acting insulin analogue as multiple-injection therapy for Type 1 diabetes improves overall glycaemic control as assessed by HbA1c and 24-h plasma glucose monitoring to a clinically significant degree, together with a reduction in nocturnal hypoglycaemia.

Sediment management in sustainable urban drainage system ponds

Since removal and disposal of sustainable urban drainage system (SUDS) sediment can incur high maintenance costs, assessments of sediment volumes, quality and frequency of removal are required. Sediment depth and quality were surveyed annually from 1999-2003 in three ponds and one wetland in Dunfermline, Scotland, UK. Highest sediment accumulation occurred in Halbeath Pond, in the most developed watershed and with no surface water management train. From comparison of measured potentially toxic metal concentrations (Cd, Cr, Cu, Fe, Ni, Pb, Zn) with standards, the average sediment quality should not impair aquatic ecosystems. 72-84% of the metal flux into the SUDS was estimated to be associated with coarse sediment (> 500 microm diameter) suggesting that management of coarse sediment is particularly important at this site. The timing of sediment removal for these SUDS is expected to be determined by loss of storage volume, rather than by accumulation of contaminants. If sediment removal occurs when 25% of the SUDS storage volume has infilled, it would be required after 17 years in Halbeath Pond, but only after 98 years in Linburn Pond (which has upstream detention basins). From the quality measurements, sediment disposal should be acceptable on adjacent land within the boundaries of the SUDS studied.

The biological variation of testosterone and sex hormone-binding globulin (SHBG) in polycystic ovarian syndrome: implications for SHBG as a surrogate marker of insulin resistance

This study was designed to assess the biological variability of total testosterone and SHBG in polycystic ovarian syndrome (PCOS) and to determine the use of SHBG as a surrogate marker of insulin resistance in PCOS. Fasting blood samples were collected at 4-d intervals on 10 consecutive occasions from 12 PCOS patients and 11 age- and weight-matched controls. Duplicate samples were analyzed for SHBG, testosterone, and insulin in a single batch, and insulin resistance was calculated by the homeostasis model assessment method (HOMA-IR). The PCOS group had higher testosterone (mean +/- SD, 3.9 +/- 0.8 vs. 3.2 +/- 1.3 nmol/liter; P = 0.001), lower SHBG (28.6 +/- 17.1 vs. 57.6 +/- 30.2 nmol/liter; P = 0.001), and greater HOMA-IR (5.85 +/- 5.3 vs. 1.67 +/- 0.63 U; P = 0.001) than the controls. In contrast to HOMA-IR (1.09 vs. 0.48 U; P = 0.001), the intraindividual variation in SHBG was lower in the PCOS group (mean, 3.4 vs. 6.3 nmol/liter; P = 0.041). The index of individuality for SHBG and testosterone in PCOS was 0.49 and 0.69, respectively. This study shows that for patients with PCOS, SHBG is an integrated marker of insulin resistance that may be of use to identify insulin-resistant individuals for targeted treatment with insulin-sensitizing agents. However, SHBG and testosterone concentrations measured in isolation are inherently unsuitable for use as tests to detect hyperandrogenemia.

Survey of diabetic retinopathy screening services in England and Wales

A postal survey of diabetologists was conducted regarding the provision of diabetic retinopathy screening services in England and Wales. About 2.5 million people had no existing or planned screening service. For the rest, the perceived percentage of patients with diabetes screened varied from less than 25% to more than 90%. Multiple modes of screening were used in most units. Lack of funding was identified as the major reason for non-provision of an adequate screening service. About 18% of the units had to use research or charitable funds for screening. Only 50% of the units using optometrists for screening had standard protocols for referral. The average wait before an ophthalmologist's opinion on sight threatening retinopathy detected by screening was unacceptably high in some units. We would suggest that establishment of identical screening protocols and provision of adequate funding on a national basis ought to be the priority if incidence of blindness from diabetic retinopathy is to be reduced according to the St Vincent Declaration.

The effects of acute hypoglycemia on relative cerebral blood flow distribution in patients with type I (insulin-dependent) diabetes and impaired hypoglycemia awareness

To examine the hypothesis that in diabetic patients with impaired hypoglycemia awareness the relative regional distribution of cerebral blood flow (rCBF) would be abnormal in a specific area, namely the frontal lobes, rCBF was examined in 20 type I diabetic patients, of whom 10 had a normal awareness of hypoglycemia and 10 had a history of impaired hypoglycemia awareness. rCBF was determined sequentially using single photon emission computed tomography (SPECT) during (1) normoglycemia (arterialized blood glucose 4.5 mmol. L-1) and (2) hypoglycemia (blood glucose 2.5 mmol.L-1) induced by a hyperinsulinemic glucose clamp technique. Distribution of the isotope, 99mTc-Exametazime, was detected using a single-slice multi-detector head scanner. A split-dose technique was used, with 250 MBq being injected during steady-state normoglycemia and 250 MBq during subsequent hypoglycemia. rCBF was estimated in 30 regions of interest, derived from a standard neuroanatomical atlas on two parallel slices at 40 and 60 mm above the orbitomeatal line (OML). No between-group differences in the pattern of overall rCBF or changes in regional tracer uptake were demonstrated. In comparison to the rCBF during normoglycemia, both patient groups exhibited significant changes in the pattern of rCBF during hypoglycemia, with increments of rCBF to both superior frontal cortices and the right thalamus and reduced rCBF to the right posterior cingulate cortex and the right putamen. This pattern of relative redistribution of rCBF during hypoglycemia was preserved in patients who had impaired hypoglycemia awareness.

Structural equation modeling of symptoms, awareness and fear of hypoglycemia, and personality in patients with insulin-treated diabetes

OBJECTIVE

To assess the possible influence of personality on self-reported awareness, symptoms, and fear of hypoglycemia and also to identify the relationship among these self-reported measures using formal structural equation modeling.

RESEARCH DESIGN AND METHODS

A structured questionnaire, which included questions about sociodemographic details, awareness of the onset of hypoglycemia, and a list of symptoms of hypoglycemia, was completed by 305 consecutive insulin-treated diabetic patients attending the diabetic clinic at the Royal Infirmary of Edinburgh. They also completed the Hypoglycemia Fear Survey (HFS), and personality was assessed using the short form of the shortened Eysenck Personality Questionnaire-Revised (EPQ-R). Formal structural equation modeling was performed using the following variables: awareness, autonomic symptoms, neuroglycopenic symptoms, severe hypoglycemic episodes in the last year, worry and behavior (from the HFS), and extroversion and neuroticism (from the short EPQ-R). This allowed a model to be constructed that expressed the putative causal associations among the variables that could be tested statistically.

RESULTS

Of the 302 patients who had experienced hypoglycemia, 111 (37%) reported reduced awareness, and these patients scored higher on the worry subscale of the HFS (reduced awareness: 41 +/- 12 vs. normal awareness: 34 +/- 12, P < 0.001). The patients with reduced awareness scored higher for neuroticism than did the patients with normal awareness (reduced awareness: 6.1 +/- 3.4 vs. normal awareness: 4.9 +/- 3.3, P < 0.01) and scored lower for extroversion (reduced awareness: 5.8 +/- 3.7 vs. normal awareness: 7.1 +/- 3.7, P < 0.01). In the structural equation modeling exercise, neuroticism was a significant putative determinant of many of the other variables.

CONCLUSIONS

Personality was the major determinant of the variance that could be accounted for in this study and influenced self-reported symptoms, awareness, and fear of hypoglycemia. Personality factors may, therefore, influence self-reports from patients, particularly when soft measures, such as symptoms, are assessed and even when using validated clinical questionnaires. This finding stresses the importance of using additional evidence, such as reports from relatives, to substantiate reports from patients of loss of hypoglycemia awareness.

PASAT performance and the pattern of uptake of 99mTc-exametazime in brain estimated with single photon emission tomography

The effect of the paced auditory serial addition test (PASAT) on the regional uptake of 99mTc-exametazime was determined by single photon emission computed tomography. Twenty insulin-treated diabetic outpatients were scanned at rest and during the performance of the PASAT task using split-dose injection of tracer. When resting and activation scans were compared there were significant decreases in tracer uptake in the right anterior cingulate and left posterior cingulate areas during PASAT activation. The findings are compared with previous studies which had implicated the anterior cingulate area in the mechanisms of attention in humans and other animals. The potentially confounding role of anxiety during attentional tasks is discussed.

Psychological and demographic correlates of glycaemic control in adult patients with type 1 diabetes

The relationship between an objective measure of glycaemic control (glycated haemoglobin (HbA1)) and personality variables was examined in two separate groups of adult Type 1 (insulin-dependent) diabetic patients. Study 1 included 121 patients, all of whom also had subjective self-reporting of treatment compliance assessed, while the first 57 patients had individual differences in intelligence, major dimensions of personality and forgetfulness documented. Study 2 examined 303 patients, all of whom had their major dimensions of personality assessed using a shortened and updated version of the original personality questionnaire. Demographic indices (age, onset-age, duration of diabetes) were assessed in both groups. No significant correlation was found between HbA1 and self-report compliance suggesting that self-reporting may be invalid as a measure of glycaemic control. In study 1 personality and intelligence variables did not correlate significantly with HbA1 values. Older patients with shorter duration of diabetes had significantly better glycaemic control (p < 0.05). A significant correlation was observed between HbA1 concentration and onset-age of diabetes (p < 0.001); the patients who had developed diabetes later in life were achieving better control of their blood glucose. In the larger number of subjects in study 2 no significant correlations were evident between HbA1 and personality variables. It is concluded that the predictors of glycaemic control indexed by HbA1 may be distinct from predictors of self-report compliance and that the latter have limited or no value in providing an assessment of quality of glycaemic control. There is no evidence of an effect of personality on glycaemic control as measured by HbA1.

Regional cerebral blood flow in IDDM patients: effects of diabetes and of recurrent severe hypoglycaemia

Chronic hyperglycaemia and recurrent severe hypoglycaemia have both been implicated as causing cerebral damage in patients with diabetes. Although cognitive dysfunction and intellectual impairment have been demonstrated in patients with recurrent severe hypoglycaemia, structural correlates have not been described, and it is not known whether specific functional changes occur in the brains of affected patients. Regional cerebral blood flow was estimated by SPECT with 99mTechnetium Exametazime in 20 patients with IDDM. Ten patients had never experienced severe hypoglycaemia and 10 had a history of recurrent severe hypoglycaemia. Patient results were compared with 20 age- and sex-matched healthy volunteers. We observed differences between the two patient groups and the control group. Tracer uptake was greater in diabetic patients in the superior pre-frontal cortex. This effect was particularly pronounced in the group who had a history of previous severe hypoglycaemia. Patients with a history of recurrent hypoglycaemia also had a relative reduction in tracer uptake to the calcarine cortex. This suggests an alteration in the pattern of baseline regional cerebral blood flow in diabetic patients with frontal excess and relative posterior reduction in cerebral blood flow.

Physiological, symptomatic and hormonal responses to acute hypoglycaemia in type 1 diabetic patients with autonomic neuropathy

The effects of peripheral autonomic neuropathy on the symptomatic, physiological, and hormonal responses to acute insulin-induced hypoglycaemia were studied in two groups of patients with Type 1 diabetes, matched for age, duration of diabetes, and prevailing glycaemic control. A group of eight patients who gave a history of normal awareness of hypoglycaemia and had normal cardiovascular autonomic function tests were compared to a group of six patients who had symptoms of autonomic dysfunction and gross abnormalities of cardiovascular autonomic function tests. An additional two patients with autonomic neuropathy who also had hypoglycaemia unawareness were studied. Acute hypoglycaemia was induced by intravenous infusion of insulin (2.5 mU kg-1 min-1) and the onset of the acute autonomic reaction (R) was identified objectively by the sudden rise in heart rate and onset of sweating. Cognitive function and hypoglycaemia symptom scores were estimated serially, and plasma counterregulatory hormones were measured. Acute autonomic activation was observed to occur in all subjects in response to hypoglycaemia and commenced at similar venous plasma glucose concentrations in both groups (neuropathic patients: 1.6 +/- 0.2 mmol l-1 vs non-neuropathic patients 1.6 +/- 0.2 mmol l-1, p = 0.9,). In the neuropathic patients plasma adrenaline responses were significantly lower at all time points from time R until time R + 30 min (MANOVA for repeated measures, F = 19.4, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Partitioning the symptoms of hypoglycaemia using multi-sample confirmatory factor analysis

The allocation of hypoglycaemic symptoms to autonomic or neuroglycopenic groups tends to occur on an a priori basis. In view of the practical need for clear symptom markers of hypoglycaemia more scientific approaches must be pursued. Substantial evidence is presented from two large scale studies we performed which support a three factor model of hypoglycaemic symptomatology, based on the statistical associations discovered among symptoms reported by diabetic patients. Study 1 involved 295 insulin-treated out-patients and found that 11 key hypoglycaemic symptoms segregated into three clear factors: autonomic (sweating, palpitation, shaking and hunger) neuroglycopenic (confusion, drowsiness, odd behaviour, speech difficulty and incoordination), and malaise (nausea and headache). The three factors were validated on a separate group of 303 insulin-treated diabetic out-patients. Confirmatory factor analyses showed that the three factor model was the optimal model for explaining symptom covariance in each group. A multi-sample confirmatory factor analysis tested the rigorous assumptions that the relative loadings of symptoms on factors across groups were equal, and that the residual variance for each symptom was identical across groups. These assumptions were successful, indicating that the three factor model was replicated in detail across these two large samples. It is suggested that the results indicate valid groupings of symptoms that may be used in future research and in clinical practice.

Changes in the anterior chamber of the eye during acute hypoglycaemia in humans

1. The changes in the volume and depth of the anterior chamber of the eye during acute insulin-induced hypoglycaemia were examined in nine healthy non-diabetic subjects (aged 23-31 years). The dimensions of the anterior chamber of the eye were measured by a photogrammetric technique, with Polaroid photographs taken of the lower half of the mid-sagittal plane of the eye at an angle of 55 degrees at a magnification of x16. Photographs were taken before and at regular intervals after the induction of acute hypoglycaemia using an infusion of unmodified (soluble) insulin at 2.5 m-units min-1 kg-1. Plasma adrenaline was measured regularly throughout the study. 2. Plasma glucose fell from 4.5 +/- 0.2 mmol/l (mean +/- SEM) to a nadir of 1.0 +/- 0.1 mmol/l (P < 0.01), which coincided with the onset of the acute autonomic reaction. Plasma adrenaline rose from 0.3 +/- 0.1 nmol/l to a peak of 3.2 +/- 0.6 nmol/l (P < 0.01) at 15 min after the autonomic reaction. 3. The volume of the anterior chamber decreased by 8.2% from 284.7 +/- 21.5 microliters at baseline to 264.5 +/- 17.0 microliters (P < 0.01) at the onset of the autonomic reaction. No significant alteration in axial anterior chamber depth was evident, but peripheral anterior depth decreased from 2.25 +/- 0.20 mm at baseline to 2.07 +/- 0.14 mm (P < 0.05) at the onset of the autonomic response.(ABSTRACT TRUNCATED AT 250 WORDS)

Frequency and morbidity of severe hypoglycaemia in insulin-treated diabetic patients

To estimate the frequency and morbidity of insulin-induced hypoglycaemia, a retrospective survey was undertaken of the frequency of severe hypoglycaemia in 600 randomly selected patients with insulin-treated diabetes who were attending a large diabetic outpatient clinic in a teaching hospital. The resulting morbidity (hypoglycaemia-related injuries, convulsions, and road traffic accidents) was ascertained in 302 patients. One hundred and seventy-five (29.2%) of the 600 patients reported a total of 964 episodes of severe hypoglycaemia in the preceding year, giving an overall frequency for the group of 1.60 episodes patient-1year-1. The frequency of severe hypoglycaemia which was documented in 544 Type 1 (ketosis prone) diabetic patients was double that observed in a subgroup of 56 Type 2 diabetic patients who were being treated with insulin (1.70 vs 0.73 episodes patient-1year-1). In the subset of 302 patients, those who had experienced severe hypoglycaemia had greater morbidity associated with an estimated rate of injury of 0.04 injuries person-1year-1. Twenty (6.6%) patients reported a total of 37 convulsions associated with hypoglycaemia, 5 of which had occurred in the preceding year (0.02 convulsions person-1year-1). Five patients reported road traffic accidents in the preceding year which had been caused by hypoglycaemia. The only reliable predictors of severe hypoglycaemia were a history of previous severe hypoglycaemia (p < 0.001), a history of hypoglycaemia-related injury (p < 0.001) or convulsion (p < 0.001), and the duration of insulin therapy (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Frequency and symptoms of hypoglycaemia experienced by patients with type 2 diabetes treated with insulin

This study ascertained the prevalence of severe hypoglycaemia and loss of awareness of hypoglycaemia in patients with Type 2 diabetes treated with insulin. One hundred and four sequentially selected Type 2 diabetic patients were compared with 104 patients with Type 1 diabetes who were matched for duration of insulin therapy. The patients were interviewed using a standardized questionnaire. During treatment with insulin, 18 Type 2 patients had experienced fewer than two episodes of hypoglycaemia, while 86 had experienced two or more episodes; 80 (93%) reported normal awareness, six (7%) reported partial awareness, and none had absent awareness of hypoglycaemia. All 86 Type 1 diabetic patients matched to the 86 Type 2 patients had experienced multiple episodes of hypoglycaemia; 71 (83%) had normal awareness, 14 (16%) had partial awareness and one patient (1%) reported absent awareness of hypoglycaemia. The Type 1 patients who had altered awareness of hypoglycaemia had longer duration of diabetes and insulin therapy (normal awareness: 5 (1-17) years (median (range)) vs partial awareness: 9 (3-18) years, p < 0.01). Similarly, Type 2 patients with altered awareness had longer duration of diabetes (normal awareness: 11 (2-25) years vs partial awareness: 19 (8-24) years, p < 0.02) and had received insulin for longer (normal awareness: 3 (1-18) years vs partial awareness: 12 (6-17) years, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Severe hypoglycemia and intelligence in adult patients with insulin-treated diabetes

The IQ scores (WAIS-R) of 100 patients with insulin-treated diabetes (aged 25-52 yr) were compared with those of 100 healthy control subjects who were matched to the diabetic patients for sex, age, education, and social class. The diabetic group had lower WAIS-R performance and verbal IQ scores than the control group (P = 0.017 and P = 0.033, respectively) after controlling for premorbid IQ. The extent of the difference was modest, representing approximately 33% of an SD in IQ. When frequency of severe hypoglycemia was controlled for the difference in performance IQ between the diabetic patient group and the control group was abolished, whereas the difference between the groups in verbal IQ persisted. It is hypothesised that cumulative severe hypoglycemia might be the major factor in the slight performance IQ differences between diabetic patients and control subjects. The origin of the verbal IQ differences, although obscure, might be related to the social impact of the disorder.

Antinatriuretic action of insulin is preserved after angiotensin I converting enzyme inhibition in normal man

To examine the potential role for intrarenal angiotensin II in mediating the antinatriuretic action of insulin, seven normal males were studied on three occasions, twice during euglycaemic hyperinsulinaemia (40 mU.m-2.min-1) after double-blind treatment for 1 week with placebo and the converting enzyme inhibitor perindopril, and on a time control day. Lithium carbonate 250 mg was given before each study as an indirect marker of tubular sodium handling. Renal haemodynamics did not change during hyperinsulinaemia. Insulin infusion reduced both the absolute and fractional urinary excretion rates of sodium (P < 0.001) and potassium (P < 0.001); these effects of insulin were not altered after converting enzyme inhibition. Lithium clearance did not change during insulin infusion on either day. The antinatriuretic effect of hyperinsulinaemia is mediated at a tubular site distal to the proximal tubule. The data does not support the hypothesis that intrarenal generation of angiotensin II plays a part in this action of insulin.

Pancreatic and pituitary hormonal responses to insulin-induced hypoglycaemia during muscarinic cholinergic blockade in man

To investigate the role of muscarinic cholinergic mechanisms in mediating the pancreatic and pituitary hormonal responses to hypoglycaemia, six normal subjects were studied during acute insulin-induced hypoglycaemia under control conditions, and during blockade with intravenous atropine. During atropine blockade the response of pancreatic polypeptide was suppressed while the maximum response of plasma glucagon was significantly higher. The increment in plasma vasopressin was also increased significantly during cholinergic blockade. During blockade with atropine the responses of plasma prolactin was reduced, with a slight but significant reduction in the growth hormone response, and although a similar maximum response of plasma ACTH was achieved, this rise was delayed. These results implicate involvement of a cholinergic muscarinic inhibitory and stimulatory mechanisms in regulating the responses of pancreatic and pituitary hormones to hypoglycaemia.

Suppression of plasma intact parathyroid hormone levels during insulin-induced hypoglycemia in humans

The adrenergic control of intact PTH secretion was investigated by measuring its plasma concentration during insulin-induced hypoglycemia in normal human subjects under control conditions (n = 12) and after alpha (n = 5)- or beta (n = 6)-adrenoceptor blockade. Blood samples were taken at baseline, at the time of the acute hypoglycemic reaction, and at regular intervals for 60 min thereafter. Plasma concentrations of intact PTH, catecholamines, total calcium, magnesium, albumin, phosphate, and glucose were measured in all subjects, and plasma ionized calcium was also assayed in three subjects during acute hypoglycemia without pharmacological blockade. At the time of the acute hypoglycemic reaction, the plasma concentration of intact PTH in the control subjects fell to 60.8% of baseline values and was accompanied by a small but significant increase in plasma total calcium. Intact PTH concentrations remained suppressed after the plasma calcium concentration had returned to normal. The two groups of subjects who were exposed to adrenoceptor blockade exhibited a reduced fall in plasma intact PTH and showed no significant increase in plasma total calcium. Therefore, insulin-induced acute hypoglycemia was associated with a fall in plasma intact PTH. Adrenoceptor blockade reduced, but did not abolish, the response, suggesting that other factors are involved.

Hospital in-patient statistics underestimate the morbidity associated with diabetes mellitus

Hospital in-patient statistics are an important outcome measurement in the assessment of the morbidity associated with diabetes mellitus. A prospective study of 157 consecutive admissions over a 28-day period compared diagnoses obtained from the clinical records with the ICD9 coding of the same admissions recorded at the Information and Statistics Division of the Scottish Health Service. Sixty-one percent of all discharge summaries omitted the diagnosis of diabetes. Even when admission was principally related to diabetes complications, 47% of medical and 88% of surgical discharge summaries omitted diabetes as a diagnostic category. ICD9 coding underestimated the percentage of admissions accounted for by diabetic patients by 100% (2.8 vs 5.6%) and as a result underestimated bed occupancy by over 200% (4.3 vs 13.7%), and is thus failing to fulfil its potential as a demographic and epidemiological record of resource use by disease classification.

Changes in renal function during acute insulin-induced hypoglycaemia in patients with type 1 diabetes

The effect of acute hypoglycaemia on renal function was examined in eight male patients with Type 1 diabetes who had normal urinary albumin excretion. Insulin was given as a bolus intravenous injection (0.125 U kg-1) and plasma glucose fell to a nadir of 1.6 (SE 0.2) mmol l-1, with all patients experiencing an acute autonomic reaction. Renal plasma flow fell from 674 (106) to 540 (198) ml min-1 during hypoglycaemia (p less than 0.01) and returned to 655 (181) ml min-1 (NS vs baseline). Glomerular filtration rate (GFR) declined from 143 (23) to 110 (36) ml min-1 during hypoglycaemia (p less than 0.02), rising to 150 (44) ml min-1 in the recovery period (NS vs baseline). The urinary flow rate and urinary albumin excretion rate both fell significantly in response to hypoglycaemia (10.6 (1.2) to 4.7 (1.1) ml min-1; p less than 0.002, and 46.2 (10.6) to 26.0 (10.5) micrograms min-1, respectively). Urinary dopamine excretion also declined, from 322 (37) to 211 (29) mumol min-1 (p less than 0.005) but sodium excretion was unchanged. Plasma adrenaline concentration (0.2 (0.03) to 1.7 (0.4) nmol l-1; p less than 0.01) and plasma renin activity (0.49 (0.13) to 1.08 (0.17) ng-Ang 1 l-1 h-1; p less than 0.01) increased during hypoglycaemia, but changes in plasma noradrenaline and angiotensin II levels did not attain significance. These acute changes in renal function, observed during hypoglycaemia in diabetic patients, may result from direct stimulation of the efferent sympathetic nerves to the kidney, complemented by the hormonal changes induced by hypoglycaemia.

Classification of symptoms of hypoglycaemia in insulin-treated diabetic patients using factor analysis: relationship to hypoglycaemia unawareness

The allocation of some symptoms of acute hypoglycaemia to autonomic and neuroglycopenic groups has proved problematical, with possible misinterpretation of studies which depend upon the use of diverse symptom questionnaires. Two hundred and ninety-five randomly selected insulin-treated diabetic patients were asked to report the symptoms which they usually experienced and believed to be caused by hypoglycaemia. Sweating, trembling, inability to concentrate, weakness, hunger and blurred vision were the most frequently reported symptoms. To classify symptoms of hypoglycaemia objectively, Factor Analysis was used to identify related symptoms which grouped together. This resulted in five groups or clusters of symptoms, four of which could be denominated as groups with a presumed common aetiology, and were labelled: 'neuroglycopenic', 'general malaise', 'autonomic', 'motor dysfunction', and 'sensory dysfunction'. The groups of symptoms derived by Factor Analysis were assessed in relation to partial or absent symptomatic awareness of hypoglycaemia based on historical evidence from the 295 insulin-treated diabetic patients. Neuroglycopenic symptoms were reported more commonly by the patients who had reported partial awareness of hypoglycaemia (number of symptoms 2.6 +/- 1.8 (mean +/- SD] than by the patients who had reported normal hypoglycaemia awareness (1.4 +/- 1.5 symptoms) (p less than 0.05). By contrast autonomic symptoms were reported less frequently by the patients who had reported absent hypoglycaemia awareness (1.3 +/- 1.4 symptoms) than by those with normal awareness (2.2 +/- 1.4 symptoms) (p less than 0.05), which was similar to the number of autonomic symptoms reported by the patients who had partial hypoglycaemia awareness (2.1 +/- 1.3 symptoms).

Hypoglycaemia unawareness in type 1 diabetes: a lower plasma glucose is required to stimulate sympatho-adrenal activation

To investigate the relationship between awareness of symptoms and the autonomic reaction of hypoglycaemia, acute hypoglycaemia was induced with intravenous insulin (2.5 mU kg-1 min-1) in diabetic and non-diabetic subjects, all of whom had normal cardiovascular autonomic function tests. Three groups were studied: (1) nine patients with Type 1 diabetes with loss of awareness of hypoglycaemia; (2) eight patients who had normal awareness of hypoglycemia, matched for duration of diabetes and blood glucose control; (3) eleven non-diabetic volunteers. The onset of the acute autonomic reaction was identified objectively by the sudden and rapid responses of heart rate and sweating. Cognitive function and hypoglycaemia symptom scores were estimated serially. Acute autonomic activation was observed to occur in all subjects in response to hypoglycaemia. In the 'unaware' diabetic patients, onset of the reaction occurred at a significantly lower plasma glucose (1.0 +/- 0.1 mmol l-1) than in the 'aware' diabetic patients (1.6 +/- 0.2 mmol l-1) (p less than 0.05) or in the non-diabetic control group (1.4 +/- 0.1 mmol l-1) (p less than 0.05). Obvious neuroglycopenia was observed only in the 'unaware' diabetic group and developed when plasma glucose had declined to approximately 1.4 +/- 0.1 mmol l-1, and thus preceded the reaction (p less than 0.02 vs the autonomic threshold). The maximal rise in plasma adrenaline was of similar magnitude in all three groups but a lower plasma glucose was required to stimulate this hormonal response in the 'unaware' patients, in whom the plasma adrenaline concentration was lower at the time of the reaction. Thus, the plasma glucose at which activation of the autonomic reaction was observed was lower in the diabetic patients with unawareness of hypoglycaemia.

Symptoms of acute insulin-induced hypoglycemia in humans with and without IDDM. Factor-analysis approach

OBJECTIVE

This study allocated the symptoms identified during acute hypoglycemia objectively to the autonomic or neuroglycopenic groups of symptoms by the use of factor analysis.

RESEARCH DESIGN AND METHODS

Twenty-five nondiabetic subjects, 14 newly diagnosed insulin-dependent diabetic patients, and 16 insulin-dependent diabetic patients with diabetes greater than 4 yr duration were studied. Acute hypoglycemia was induced with insulin (2.5 mU.kg-1 body wt.min-1 i.v.), and symptoms of hypoglycemia were recorded with a seven-point scale at regular time points throughout the studies. Factor analysis of the symptom scores at the time of the acute autonomic reaction with principal component analysis followed by Varimax rotation was used to separate those symptoms that might belong to neuroglycopenic and autonomic groups.

RESULTS

Hypoglycemia was induced to a mean +/- SE plasma glucose nadir of 1.3 +/- 0.1 mM in nondiabetic subjects, to 2.0 +/- 0.3 mM in newly diagnosed diabetic patients, and 1.4 +/- 0.2 mM in patients with diabetes of greater than 4 yr duration. The most frequently reported autonomic symptoms were sweating, trembling, and warmness, and the most frequently reported neuroglycopenic symptoms were inability to concentrate, weakness, and drowsiness. Neuroglycopenic symptoms were reported more commonly at the onset of hypoglycemia, which was identified by the development of symptoms. Factor analysis grouped trembling, anxiety, sweating, warmness, and nausea together, and this grouping was labeled an autonomic factor. A second factor was identified that included dizziness, confusion, tiredness, difficulty in speaking, shivering, drowsiness, and inability to concentrate, which was labeled a neuroglycopenic factor.

CONCLUSIONS

This study demonstrated the high frequency with which neuroglycopenic symptoms occur at the onset of hypoglycemia and the symptoms that could be used by an individual patient as a warning of the development of acute hypoglycemia, although the rapid reduction of plasma glucose is faster than experienced by the ambulant diabetic patient. Factor analysis assisted with the allocation of symptoms to either the autonomic or neuroglycopenic groupings, but the allocation of some symptoms remained undefined, and care must be taken when assessing symptoms such as hunger, weakness, blurred vision, and drowsiness when comparing the frequency of autonomic versus neuroglycopenic symptoms. To reduce the confusion resulting from the use of different symptom questionnaires in studies of hypoglycemia, a sample questionnaire is presented, the development of which was assisted by our analysis.

Effect of alpha-adrenergic blockade on pituitary hormonal responses to insulin-induced hypoglycemia in humans

Arginine vasopressin, oxytocin and ACTH are released from the pituitary gland in response to acute hypoglycemia. To investigate the role of alpha-adrenergic mechanisms in mediating this response, 6 non-diabetic subjects were studied during hypoglycemia induced by 0.15 IU/kg i.v. insulin under control conditions, and during non-selective alpha-adrenergic blockade with phentolamine. In the control study plasma arginine vasopressin rose from 1.6 +/- 0.8 pmol/l (mean +/- SEM) basally to a maximum of 2.5 +/- 0.8 pmol/l following hypoglycemia (p less than 0.05). An exaggerated response was found during phentolamine blockade, with a maximum plasma vasopressin of 11.5 +/- 0.4 pmol/l (by analysis of variance, p less than 0.05). The plasma oxytocin response to hypoglycemia was similarly increased during phentolamine compared to control. Plasma growth hormone rose to 94 +/- 19 mU/l, and during blockade with phentolamine the response was significantly reduced reaching a peak of 34 +/- 7 mU/l (by analysis of variance, p less than 0.05). ACTH and prolactin both increased in response to hypoglycemia, but the increases were not affected by phentolamine. An alpha-adrenergic mechanism appears to inhibit the release of arginine vasopressin and oxytocin in response to hypoglycemia, but does not appear to affect the secretion of ACTH.

Effects of adrenergic blockade on serum potassium changes in response to acute insulin-induced hypoglycemia in nondiabetic humans

OBJECTIVE

To determine the possible role of adrenergic mechanisms in mediating the fall in serum potassium concentration after intravenous injection of insulin.

RESEARCH DESIGN AND METHODS

Eighteen nondiabetic male volunteers, divided into three groups of six subjects, comprised the study. Hypoglycemia was induced by a bolus of short-acting insulin (0.15 U/kg body wt). Six subjects were studied in control conditions, six during alpha-adrenergic blockade with phentolamine, and six during beta-adrenergic blockade with propranolol.

RESULTS

In the control group, there was an immediate fall in serum potassium from 4.0 +/- 0.1 to 3.6 +/- 0.1 mM at baseline + 15 min. After the onset of acute hypoglycemia, potassium decreased further in the control group, reaching a lowest concentration of 3.3 +/- 0.1 mM. In the propranolol group, the late decrease in potassium was inhibited, and there were no further changes in serum potassium. During alpha-blockade, there was an exaggerated fall to 2.6 +/- 0.1 mM at 30 min after the onset of hypoglycemia.

CONCLUSIONS

The later fall in serum potassium, which occurs after the onset of hypoglycemia, is probably mediated by stimulation of beta-adrenoreceptors, whereas coincidental stimulation of alpha-adrenoreceptors opposes this fall in potassium and may prevent the development of severe hypokalemia in response to acute hypoglycemia.

Cumulative cognitive impairment following recurrent severe hypoglycaemia in adult patients with insulin-treated diabetes mellitus

To examine the hypothesis that episodes of severe hypoglycaemia may cause cumulative cognitive impairment. 100 Type 1 (insulin-dependent) diabetic patients were examined. Their age range was 25-52 years, and the onset of diabetes had occurred after the age of 19 years. Patients with evidence of organic brain disease, including cerebrovascular disease, were excluded. A questionnaire was used to assess the number, frequency and severity of hypoglycaemic episodes experienced during treatment with insulin and the accuracy of this retrospective information was verified from general practice and hospital case-notes. A detailed neuropsychological assessment was undertaken, including tests of pre-morbid and present IQ (Wechsler-Revised), memory and information-processing speed. Significant correlations were observed between the frequency of severe hypoglycaemia and the magnitude of intellectual decline, Performance IQ, inspection time and reaction time (patients with the more frequent hypoglycaemia had poorer performance). Two sub-groups of patients were identified on the basis of their experience of severe hypoglycaemia, and were balanced for pre-morbid IQ, age and duration of diabetes. One sub-group (n = 23) had never experienced severe hypoglycaemia (Group A), whilst the other sub-group (n = 24) had suffered at least five episodes of severe hypoglycaemia (Group B). Group B had greater intellectual impairment than Group A, and Group B also had a significantly slower mean reaction time and higher reaction time variance when compared with Group A.

Autonomic mechanisms underlying intraocular pressure changes during insulin-induced hypoglycaemia in normal human subjects: effects of pharmacological blockade

1. A fall in intraocular pressure is induced by acute hypoglycaemia in humans. The role of the autonomic nervous system in mediating this response was investigated in 24 normal volunteers in whom hypoglycaemia was induced with intravenous soluble insulin, under four experimental conditions: (1) control (n = 6), (2) non-selective alpha-adrenoceptor blockade (phentolamine) (n = 6), (3) non-selective beta-adrenoceptor blockade (propranolol) (n = 6) and (4) cholinergic blockade (atropine) (n = 6). Intraocular pressure was measured by using an applanation tonometer. In 12 subjects intraocular pressure was measured during each type of pharmacological blockade of similar duration without induction of hypoglycaemia, to assess the effects of individual antagonists. 2. In the control study intraocular pressure fell during hypoglycaemia from 15 +/- 1.0 to 10 +/- 1.3 mmHg (P less than 0.01) 10 min after the autonomic reaction. beta-Adrenoceptor blockade caused a reduction in intraocular pressure from 15 +/- 1.1 to 9 +/- 1.0 mmHg (P less than 0.001) before the administration of insulin, and when hypoglycaemia was induced intraocular pressure decreased further to 7 +/- 1.0 mmHg (P less than 0.05, compared with immediately before insulin). A decrease in intraocular pressure of similar magnitude was observed with propranolol alone (16 +/- 1.0 to 10 +/- 1.0 mmHg, P less than 0.05). 3. Cholinergic blockade had no immediate effect on intraocular pressure, and the reduction in intraocular pressure during hypoglycaemia was of similar magnitude to that observed during the control study.(ABSTRACT TRUNCATED AT 250 WORDS)

Can prepregnancy care of diabetic women reduce the risk of abnormal babies?

OBJECTIVE

To see whether a prepregnancy clinic for diabetic women can achieve tight glycaemic control in early pregnancy and so reduce the high incidence of major congenital malformation that occurs in the infants of these women.

DESIGN

An analysis of diabetic control in early pregnancy including a record of severe hypoglycaemic episodes in relation to the occurrence of major congenital malformation among the infants.

SETTING

A diabetic clinic and a combined diabetic and antenatal clinic of a teaching hospital.

PATIENTS

143 Insulin dependent women attending a prepregnancy clinic and 96 insulin dependent women managed over the same period who had not received specific prepregnancy care.

MAIN OUTCOME MEASURE

The incidence of major congenital malformation.

RESULTS

Compared with the women who were not given specific prepregnancy care the group who attended the prepregnancy clinic had a lower haemoglobin AI concentration in the first trimester (8.4% v 10.5%), a higher incidence of hypoglycaemia in early pregnancy (38/143 women v 8/96), and fewer infants with congenital abnormalities (2/143 v 10/96; relative risk among women not given specific prepregnancy care 7.4 (95% confidence interval 1.7 to 33.2].

CONCLUSION

Tight control of the maternal blood glucose concentration in the early weeks of pregnancy can be achieved by the prepregnancy clinic approach and is associated with a highly significant reduction in the risk of serious congenital abnormalities in the offspring. Hypoglycaemic episodes do not seem to lead to fetal malformation even when they occur during the period of organogenesis.

Unawareness of hypoglycaemia in insulin-treated diabetic patients: prevalence and relationship to autonomic neuropathy

Three-hundred and two insulin-treated diabetic patients were questioned about hypoglycaemia using a structured questionnaire interview. Two-hundred and twenty-six patients (75%) had normal symptomatic awareness, 48 (16%) had partial awareness, 21 (7%) had absent awareness of hypoglycaemia, and 7 (2%) denied ever experiencing hypoglycaemia. Patients with complete loss of awareness of hypoglycaemia had diabetes of longer duration; none had a HbA1 concentration within the non-diabetic range. Loss of awareness of hypoglycaemia was associated with an increased incidence of severe hypoglycaemia, 19 (91%) of the patients with absent awareness, and 33 (69%) with partial awareness of hypoglycaemia experiencing severe hypoglycaemia over 1 year compared with only 41 (18%) of patients with normal awareness of hypoglycaemia (p less than 0.001). Cardiovascular autonomic function tests were performed in 226 (75% of the whole group). Of the patients who had diabetes for more than 15 years, 54% (n = 39) with normal awareness of hypoglycaemia, compared with 59% (n = 10) with absent awareness of hypoglycaemia, had evidence of cardiovascular autonomic impairment (NS). Seven (41%) of the 17 patients with absent awareness of hypoglycaemia and diabetes of greater than 15 years duration had no evidence of autonomic dysfunction. Loss of hypoglycaemia awareness is a common problem in patients with insulin-treated diabetes of long duration, is associated with an increased incidence of severe hypoglycaemia, but is not invariably associated with abnormal cardiovascular autonomic function tests.

Leucocyte mobilization and release of neutrophil elastase following acute insulin-induced hypoglycaemia in normal humans

Insulin-induced hypoglycaemia in humans is associated with the rapid mobilization of leucocytes in peripheral blood. The aim of the present study was to determine whether neutrophil activation, manifested in plasma by neutrophil elastase concentration, occurs in response to insulin-induced hypoglycaemia. Acute hypoglycaemia (mean blood glucose 1.3 +/- 0.2 mmol l-1; mean +/- SD) was induced with intravenous insulin in 15 normal human subjects, and provoked an increase in the neutrophil count from 3.4 (range 1.9-6.5) to 10.7 (9.4-16.3) X 10(9) l-1 (p less than 0.001), and in the total leucocyte counts from 5.7 (4.1-8.1) to 12.8 (11.3-18.6) X 10(9) l-1 (p less than 0.001), with associated elevations in plasma neutrophil elastase concentration from 21 (12-34) to 29 (14-70) micrograms l-1 (p less than 0.05), and in total neutrophil elastase concentration from 5.90 (3.13-8.20) to 25.20 (23.00-52.00) mg l-1 (p less than 0.001). As neutrophil elastase is implicated in the development of vascular disease, this rise in response to hypoglycaemia may be of pathological importance in insulin-treated diabetic patients.

Cardiac responses to acute insulin-induced hypoglycemia in humans

The effects of acute hypoglycemia on the heart and cardiovascular system were examined in humans using radioisotopic techniques, complemented by measurement of heart rate and blood pressure. The heart rate increased from 62 +/- 3 to 87 +/- 3 beats/min in response to hypoglycemia; this increase was accompanied by a significant increase in systolic blood pressure, a fall in diastolic blood pressure, with no change in the mean arterial blood pressure. The left ventricular ejection fraction increased from 47 +/- 3 (SE) to 72 +/- 5% in response to hypoglycemia. The increases in heart rate and ejection fraction were abolished during parenteral nonselective beta-adrenergic blockade with propranolol but were unaffected by either alpha-adrenergic blockade with phentolamine or cholinergic blockade with atropine. During beta-adrenergic blockade, there were significant increases in diastolic and mean arterial blood pressure in response to hypoglycemia. During alpha-adrenergic blockade the systolic, diastolic, and mean arterial pressures fell significantly after hypoglycemia. The blood pressure responses to hypoglycemia were unaffected by cholinergic blockade. Thus the increases in ejection fraction and in heart rate in response to hypoglycemia are mediated by beta-adrenoreceptors, whereas the blood pressure responses to hypoglycemia are mediated by alpha- and by beta-adrenoreceptors.

Comparison of intramuscular glucagon and intravenous dextrose in the treatment of hypoglycaemic coma in an accident and emergency department

Hypoglycaemia remains a serious and much feared complication of insulin therapy. In this study, patients attending an accident and emergency department in hypoglycaemic coma were randomized to treatment with either intravenous dextrose (25g) or intramuscular glucagon (1mg), administered into the right thigh. Restoration of normal conscious level was slower after glucagon than dextrose (9.0 vs 3.0 min, P less than 0.01), although the average duration of hypoglycaemic coma was 120 min. Two patients in the glucagon-treated group, who failed to show satisfactory recovery after 15 min, required additional treatment with intravenous dextrose. On questioning following recovery, all except two patients reported loss of awareness of the onset of hypoglycaemia Intramuscular glucagon is valuable in the treatment of severe hypoglycaemia outwith hospital and, although the slightly slower and less predictable recovery may appear to make it a less attractive option than intravenous dextrose in the accident and emergency department, this must be balanced against the advantages of ease of administration and a lower incidence of serious adverse effects.

Splenic responses to acute insulin-induced hypoglycaemia in humans

1. The effects of acute hypoglycaemia on the spleen were examined in normal humans using radioisotopic techniques, complemented by ultrasonic examination of the spleen. Hypoglycaemia had a modest effect on splenic area, measured by ultrasonography, which declined to 62 +/- 6% (mean +/- SEM) of the basal value after the onset of the acute hypoglycaemic reaction. 2. Hypoglycaemia had a pronounced effect on the splenic radioactivity, which decreased significantly to a mean of 10 +/- 7% of basal radioactivity at 15 min after the onset of hypoglycaemia. The splenic image completely disappeared at some time after hypoglycaemia in all subjects. 3. The reduction of splenic radioactivity was abolished during non-selective alpha-adrenergic blockade with phentolamine, but was unaffected by beta-adrenergic blockade with propranolol, or cholinergic blockade with atropine, which suggests that the response of vessels perfusing the spleen is mediated by alpha-adrenoceptors.

The effect of alpha-adrenergic blockade on responses of peripheral blood cells to acute insulin-induced hypoglycaemia in humans

Acute hypoglycaemia provokes rapid changes in peripheral blood cell counts. To examine possible adrenergic mechanisms modulating these changes, counts of peripheral blood cells including lymphocytes, granulocytes and erythrocytes were measured in response to acute hypoglycaemia in a group of six normal subjects in control conditions (study 1), and during alpha-adrenergic blockade with phentolamine (study 2). In study 1 hypoglycaemia provoked a biphasic leucocyte response, with an early rise in lymphocyte count and a later rise in granulocyte count. The erythrocyte count increased modestly following hypoglycaemia. During alpha-adrenergic blockage, the rise in total leucocyte count was diminished, with the rise in the lymphocyte count being greatly obtunded. These findings suggest that the increments of peripheral lymphocyte and erythrocyte counts in response to acute insulin-induced hypoglycaemia are mediated via alpha-adrenoreceptors.

The effects of acute insulin-induced hypoglycaemia on renal function in normal human subjects

The effects of acute insulin-induced hypoglycaemia on renal function were studied in 8 normal male subjects. Plasma glucose (mean (SE) fell from 4.6(0.2) to 1.3(0.2) mmol l(-1), the nadir being coincident with the acute autonomic reaction, and returned to the basal value over the following 120 min. Glomerular filtration rate declined from 118(6) to 95(4) ml min-1 at the glucose nadir (p less than 0.01), and during the recovery phase returned to 118(7) ml min-1 (NS compared with basal). Renal plasma flow fell from 625(38) to 485(27) ml min-1 (p less than 0.01), rising to 545(46) ml min-1 during recovery from hypoglycaemia (NS compared with basal). Following hypoglycaemia, urinary excretion of sodium and dopamine were reduced significantly, but the albumin excretion rate was unchanged. Plasma concentrations of adrenaline, noradrenaline, angiotensin II, and plasma renin activity increased in response to hypoglycaemia. These acute changes in renal function are probably caused by sympatho-adrenal activation and secretion of catecholamines, but other hormones, such as angiotensin II, may be contributory.

Symptomatic awareness of hypoglycaemia: does it change on transfer from animal to human insulin?

A retrospective survey of symptomatic awareness of hypoglycaemia was performed in 189 randomly selected patients with insulin-treated diabetes who had been transferred from highly purified animal insulins to human insulin in the preceding 24 months. Of the 189 patients 44 (23%) complained of chronic hypoglycaemic unawareness, unrelated to ambient blood glucose control, before change of insulin species. Only 12 of the remaining 145 patients reported a reduction in awareness of hypoglycaemia following transfer to human insulin (6% of the whole group), while 6 (3%) reported an increase in awareness following the transfer. The 12 patients reporting reduced awareness had a mean duration of diabetes of 24 +/ 10 years compared to a duration of 15 +/- 10 years in the patients with normal awareness. The mean glycosylated haemoglobin concentrations were similar in all of the groups of patients. Six patients had developed total loss of awareness of the onset of hypoglycaemia, with all but one patient having suffered multiple episodes of severe hypoglycaemia. This reduced hypoglycaemic awareness on human insulin therapy was not associated with any significant improvement in blood glucose control.

Hypoglycemic convulsions cause serious musculoskeletal injuries in patients with IDDM

Six diabetic patients are described who sustained serious musculoskeletal injuries during insulin-induced hypoglycemia. The convulsions were associated with nocturnal hypoglycemia, superoptimal glycemic control, pregnancy, hypoglycemic unawareness, or errors in self-management.