Non-diabetic Volunteers Research Articles

Growth of Candida albicans on the stratum corneum of diabetic and non‐diabetic patients

We have used a novel approach to in vitro culture of Candida albicans on cyanoacrylate skin surface strippings. It appears that with this model yeasts and hyphae grew on large surfaces of stratum corneum. The area of extension of the fungal growth was larger on stratum corneum taken from diabetic than from non-diabetic volunteers.

Contribution of Impaired Muscle Glucose Clearance to Reduced Postabsorptive Systemic Glucose Clearance in NIDDM

The reduced postabsorptive rates of systemic glucose clearance in non-insulin-dependent diabetes mellitus (NIDDM) are thought to be the consequence of insulin resistance in peripheral tissues. Although the peripheral tissues involved have not been identified, it is generally assumed to be primarily muscle, the major site of insulin-mediated glucose disposal. To test this hypothesis, we measured postabsorptive systemic and forearm glucose utilization and clearance in 15 volunteers with NIDDM and 15 age- and weight-matched nondiabetic volunteers. Although systemic glucose utilization was increased in NIDDM subjects (14.5 +/- 0.5 vs. 11.2 +/- 0.2 mumol.kg-1.min-1, P less than 0.001), systemic glucose clearance was reduced 1.40 +/- 0.06 vs. 2.13 +/- 0.05 ml.kg-1.min-1, P less than 0.01). Although forearm glucose utilization was increased in NIDDM subjects (0.663 +/- 0.058 vs. 0.411 +/- 0.019 mumol.dl-1.min-1, P less than 0.001), forearm glucose dl-1 clearance was reduced (0.628 +/- 0.044 vs. 0.774 +/- 0.037 ml.L-1.min-1, P less than 0.01). However, extrapolation of forearm data to total-body muscle indicated that impaired clearance reduced muscle glucose disposal by only 61 +/- 21 mumol/min, whereas impaired systemic clearance reduced systemic glucose disposal by 662 +/- 82 mumol/min. Thus, impaired muscle glucose clearance accounted for less than 10% of the reduced systemic glucose clearance in NIDDM subjects. Therefore, we conclude that muscle insulin resistance plays only a minor role in the reduced systemic glucose clearance found in NIDDM in the postabsorptive state and propose that reduced brain glucose clearance is largely responsible.

Mapping Diabetic Sensory Neuropathy by Current Perception Threshold Testing

Detailed clinical neurological examinations were conducted on 44 nondiabetic volunteers and 59 diabetic subjects. The examinations focused particularly on sensory symptomatic and physical evaluation. Standardized assessment of symptoms and physical testing of light touch, pain, vibratory, and thermal sensation was performed at the hand, wrist, elbow, foot, ankle, and knee. A total symptom score and physical score were defined by summing test scores at each site. Current perception threshold (CPT) testing that used constant sine-wave-alternating current was conducted at the same anatomic sites. CPT correlations with the physical score gave r values of .55 for 5 Hz, .60 for 250 Hz, and .62 for 2000 Hz (n = 618). Correlations with the symptom score were not as strong: r = .45 for 5 Hz, .46 for 250 Hz, and .51 for 2000 Hz. The correlation with symptom score was due primarily to a strong relationship for the symptom of numbness (r = .53 for all 3 frequencies). Correlations with pain and paresthesia were much lower. CPTs for diabetic subjects at the three frequencies were higher at most locations than for the nondiabetic volunteers. However, CPTs were no different from normal values in diabetic subjects without evidence of neuropathy. CPT testing appears to be a useful technique for assessment of diabetic sensory neuropathy.

Motor vehicle driving among diabetics taking insulin and non-diabetics.

To determine whether rates of road traffic accidents were higher in diabetics treated with insulin than in non-diabetic subjects. Controlled, five year retrospective survey. Diabetic, dermatology, and gastroenterology outpatient clinics. 596 Diabetics treated with insulin (354 drivers) aged 18-65 attending two clinics and 476 non-diabetic outpatients (302 drivers). Rates of accidents in diabetic and non-diabetic subjects. A self completed questionnaire was used to record age, sex, driving state, and rates of accidents and convictions for motoring offences among diabetic and non-diabetic volunteers. For the diabetic volunteers further information was obtained on treatment, experience of hypoglycaemia, and declaration of disability to the Driving and Vehicle Licensing Centre and their insurance company. Accident rates were similar (81 (23%) diabetic and 76 (25%) non-diabetic drivers had had accidents in the previous five years). A total of 103 diabetic drivers had recognised hypoglycaemic symptoms while driving during the previous year. Only 12 reported that hypoglycaemia had ever caused an accident. Overall, 249 had declared their diabetes to an insurance company. Of these, 107 had been required to pay an increased premium, but there was no excess of accidents in this group. Diabetic drivers treated with insulin and attending clinics have no more accidents than non-diabetic subjects and may be penalised unfairly by insurance companies.

Clinical photon correlation spectroscopy evaluation of human diabetic lenses

Clinical research on cataract prevention requires an in vivo assessment of the lens of the eye that is non-invasive, quantitative and detects lens changes that precede lens opacification or cataract formation. The method of photon correlation spectroscopy of quasi-elastic light scattering spectroscopy provides such a non-invasive probe. The measurement, based on fluctuations in scattered light intensity caused by translational Brownian motion of the lens proteins, allows a determination of a protein diffusion coefficient and hence information on quaternary conformational changes of these protein scatterers. These protein changes have been observed in association with the presence of lens opacification. The occurrence of these changes prior to opacification, however, has still to be established. The analyses performed in this study were aimed at testing the hypothesis of an association between subclinical molecular changes in the lens as measured by quasi-elastic light scattering and the presence of selected risk factors for cataract. Measurements were made from 393 diabetics attending the Joslin Diabetes Center Eye Unit and 38 non-diabetic volunteers. Measurements at two different instrument sample times, 1·5 μsec and 150 μsec, allowed characterization of two different protein size distributions contributing to the quasi-elastically light scattered signal. Measurements performed at the 1·5 μsec sample time demonstrated significantly decreased lens protein diffusivity in association with older age, higher grade of nuclear sclerosis and presence of diabetes. Statistically significant associations were also observed between lens protein diffusivity and diabetes related factors such as glycosylated hemoglobin level (diabetes control), duration of diabetes, age at onset of diabetes and type of diabetic therapy. The pattern of association exhibited between decreased protein diffusion coefficient and risk factor status is consistent with the patterns of increased risk previously demonstrated in cataract formation. Measurements performed at the 150 μsec sample time demonstrated significantly decreased lens protein diffusivity in association with increasing age, female sex and glycosylated hemoglobin level. These associations differed significantly from those observed at the 1·5 μsec sample time, thereby suggesting that these two sample times assess different species of lens proteins. The results of this analysis demonstrate the clinical utility of quasi-elastic light scattering as a rapid, non-invasive method to quantitate lens changes and assess methods of cataract prevention and treatment.

Effects of physiological increases in plasma noradrenaline on the human endocrine pancreas

The effect of plasma noradrenaline concentrations within the physiological range (less than 5-6 nM) on the endocrine pancreas was investigated in 9 nondiabetic volunteers. Noradrenaline significantly inhibited plasma insulin levels but did not change plasma glucagon and somatostatin concentrations.

Predominant role of gluconeogenesis in increased hepatic glucose production in NIDDM.

Excessive hepatic glucose output is an important factor in the fasting hyperglycemia of non-insulin-dependent diabetes mellitus (NIDDM). To determine the relative contributions of gluconeogenesis and glycogenolysis in a quantitative manner, we applied a new isotopic approach, using infusions of [6-3H]glucose and [2-14C]acetate to trace overall hepatic glucose output and phosphoenolpyruvate gluconeogenesis in 14 postabsorptive NIDDM subjects and in 9 nondiabetic volunteers of similar age and weight. Overall hepatic glucose output was increased nearly twofold in the NIDDM subjects (22.7 +/- 1.0 vs. 12.0 +/- 0.6 mumol.kg-1.min-1 in the nondiabetic volunteers, P less than .001); phosphoenolpyruvate gluconeogenesis was increased more than threefold in the NIDDM subjects (12.7 +/- 1.4 vs. 3.6 +/- 0.4 mumol.kg-1.min-1 in the nondiabetic subjects, P less than .001) and was accompanied by increased plasma lactate, alanine, and glucagon concentrations (all P less than .05). The increased phosphoenolpyruvate gluconeogenesis accounted for 89 +/- 6% of the increase in overall hepatic glucose output in the NIDDM subjects and was significantly correlated with the fasting plasma glucose concentrations (r = .67, P less than .01). Glycogenolysis, calculated as the difference between overall hepatic glucose output and phosphoenolpyruvate gluconeogenesis, was not significantly different in the NIDDM subjects (9.9 +/- 0.06 mumol.kg-1.min-1) and the nondiabetic volunteers (8.4 +/- 0.3 mumol.kg-1.min-1). We conclude that increased gluconeogenesis is the predominant mechanism responsible for increased hepatic glucose output in NIDDM.

Thromboxane biosynthesis and platelet function in type I diabetes mellitus.

It has been speculated that platelet activation may contribute to the evolution of vascular complications in patients with Type I diabetes mellitus. To address this hypothesis, we measured the plasma and urinary metabolites of thromboxane, presumably of platelet origin, and of prostacyclin, derived from endothelial cells, in addition to more conventional indexes of platelet function. Urinary excretion of the metabolites 2,3-dinor-thromboxane B2 and 2,3-dinor-6-keto-prostaglandin F1 alpha did not differ between diabetics with or without retinopathy and nondiabetic controls. Furthermore, measurement of platelet granule constituents, the aggregation responses to ADP or arachidonic acid, and levels of serum thromboxane B2 failed to discriminate between the groups. The institution of tight diabetic control with multiple daily injections of insulin failed to alter either urinary metabolite excretion or plasma levels of 11-dehydro-thromboxane B2. Conversely, insulin-induced hypoglycemia failed to alter the concentrations of plasma or urinary thromboxane metabolites in nondiabetic volunteers, despite a mean 60-fold increase in plasma epinephrine. These studies suggest that platelet activation does not precede the development of microvascular complications in patients with Type I diabetes who lack clinical evidence of macrovascular disease and have normal renal function. Furthermore, it is unlikely that platelet activation due to intermittent hypoglycemia contributes to the reportedly accelerated development of retinopathy in such patients, when they are subject to tight diabetic control.

Quantification of the relative impairment in actions of insulin on hepatic glucose production and peripheral glucose uptake in non-insulin-dependent diabetes mellitus

In non-insulin-dependent diabetes mellitus (NIDDM), both liver and peripheral tissues are resistant to insulin, but the relative severity and contribution of these abnormalities to fasting hyperglycemia are poorly understood. We, therefore, determined the dose-response characteristics for insulin-mediated suppression of hepatic glucose production (GP) and stimulation of peripheral glucose uptake (GU) in 14 NIDDM subjects and 14 age- and weight-matched nondiabetic volunteers (NV) using the glucose clamp sequential insulin infusion technique along with isotopic estimation of glucose flux. Postabsorptive rates of both GP (94 ± 7 v 72 ± 2 mg/M 2/min in NV, P < .01) and GU (88 ± 5 v 72 ± 2 in NV, P < .01) were significantly increased in NIDDM subjects. The ED 50 (half-maximally effective plasma insulin concentration) in NIDDM subjects for suppression of GP (64 ± 14 μU/mL) and stimulation of GU (118 ± 20 μU/mL were both increased more than twofold above normal (26 ± 2 and 58 ± 5 μU/mL, respectively, both P < .01) and were significantly correlated with one another ( r = .68, P < .01). Although GP could be totally suppressed in the NIDDM subjects, their maximal GU was reduced 30% (287 ± 20 v 372 ± 15 mg/m 2/min in NV, P < .01). Nevertheless, at all physiologically relevant plasma insulin concentrations studied, there was comparable impairment in GP and GU responses. Moreover, fasting plasma glucose concentrations in NIDDM subjects were highly correlated with their increased basal rates of GP ( r = .81, P < .005) but not with their reduced GU. We conclude that hepatic and peripheral tissues are equally resistant to insulin in NIDDM. Because insulin exerts an appreciable suppressive effect on hepatic GP in the postabsorptive state when only 20% to 30% of GU is insulin-mediated, our findings suggest that hepatic, rather than peripheral, insulin resistance is the major factor responsible for fasting hyperglycemia in this disorder.

Subnormal pancreatic polypeptide and epinephrine responses to insulin-induced hypoglycemia identify patients with insulin-dependent diabetes mellitus predisposed to develop overt autonomic neuropathy.

Sixteen patients with insulin-dependent diabetes mellitus with no current evidence of autonomic dysfunction underwent an insulin tolerance test during which plasma pancreatic polypeptide and epinephrine responses were determined. Compared to 11 age- and weight-matched nondiabetic volunteers, 9 diabetic subjects had subnormal plasma pancreatic polypeptide responses (n = 6) or plasma epinephrine responses (n - 8). When autonomic function was reassessed 2 to 3 years later by standard cardiovascular reflex tests and clinical examination, 8 of 9 diabetic subjects with subnormal hormonal responses to hypoglycemia developed either abnormal cardiovascular reflexes (6 of 9) or overt symptoms consistent with diabetic autonomic neuropathy (6 of 9), whereas none of the subjects with previously normal plasma pancreatic polypeptide and epinephrine responses did (P less than 0.01). Diminished pancreatic polypeptide and epinephrine responses to hypoglycemia can predict the development of overt autonomic neuropathy in patients with insulin-dependent diabetes mellitus; identification of patients with a predilection to develop autonomic neuropathy may permit earlier treatment.

Serum fructosamine concentration as measure of blood glucose control in type I (insulin dependent) diabetes mellitus.

Serum fructosamine activity was studied in 42 patients with type I (insulin dependent) diabetes mellitus and 30 non-diabetic volunteers as an index of blood glucose control. There was a significant correlation both between fructosamine and glycosylated haemoglobin values (r = 0.82) and between fructosamine and the fasting C peptide concentration (r = -0.81). Test results in 14 of the diabetics reflected the mean plasma glucose concentration calculated from 25 serial estimations in a single 24 hour period (r = 0.75; p less than 0.01) but not the mean amplitude of glycaemic excursion (r = 0.23; p greater than 0.05). Fructosamine concentrations measured in these multiple blood specimens did not change significantly throughout the day (mean coefficient of variation 4.1%) despite wide variability of the respective plasma glucose concentrations (mean coefficient of variation 36.2%). It is concluded that a single random serum sample analysed for fructosamine concentration provides a simple and reliable assessment of glucose homoeostasis in patients with type I diabetes mellitus.

Mechanism and significance of insulin resistance in non-insulin-dependent diabetes mellitus.

To determine whether receptor and/or postreceptor abnormalities of insulin action were responsible for insulin resistance in nonobese patients with non-insulin-dependent diabetes mellitus (NIDDM) and to assess the role of insulin resistance in their impaired glucose tolerance, insulin dose-response characteristics, insulin binding to monocytes, and insulin secretion were compared in 10 nonobese patients with NIDDM and six age-weight-matched nondiabetic volunteers. The insulin resistance of the diabetics was characterized by a shift to the right of their insulin dose-response curve (Km 81 +/- 4 microunits/ml vs. 58 +/- 2 microunits/ml in the nondiabetics P less than 0.001) but a normal maximal response to insulin. Although monocyte insulin binding was decreased in the diabetics (P less than 0.01), their response to insulin was appropriate for the number of insulin receptors occupied indicating normal postreceptor function. Insulin secretion was markedly reduced in diabetic subjects (52 +/- 22 vs. 471 +/- 90 microunits . ml-1 . 10 min-1 in the nondiabetic subjects, P less than 0.001) and was more strongly correlated with fasting plasma glucose (r = 0.92, P less than 0.001) and intravenous glucose tolerance (Kivgtt) (r = 0.98, P less than 0.001) than was insulin sensitivity (Km) (r = 0.23, NS, and r = 0.57, P less than 0.05, respectively). We conclude that in nonobese patients with NIDDM, insulin resistance is characterized by a shift to the right of the insulin dose-response curve, which can be accounted for solely by an insulin receptor defect. However, in these patients, impaired insulin secretion rather than insulin resistance appears to be the predominant metabolic abnormality.

Endogenous Insulin Secretion Measured by C-peptide in Maturity-Onset Diabetes Controllable by Diet Alone

Endogenous insulin secretion was quantified in patients with maturity-onset diabetes (MOD) whose diabetes was controllable solely by caloric regulation as primary therapy. Insulin was used adjunctively only and persistent attempts were made to withdraw it as weight loss occurred in response to diet. Insulin secretory capacity was measured by C-peptide response during a standard 100-g oral glucose tolerance test in 24 patients who achieved normalization of plasma glucose level as a result of dietary therapy alone. Summed C-peptide levels for the diet-controlled diabetic patients was 7.8 +/- 0.7 pmol/mL as compared with 6.1 +/- 0.45 pmol/mL for a group of ten normal-weight, nondiabetic volunteers.

Recovery from decompensated non-insulin-dependent diabetes mellitus: studies of C-peptide secretion.

Eleven non-insulin-dependent diabetic patients presented with decompensated hyperglycemia. Nine had pronounced ketonuria, five with acidosis. In seven cases, precipitating factors were identified. In the other four cases, including three cases of diabetic ketoacidosis, no identifiable triggering events were present. In each case, recovery from the initially decompensated diabetic state occurred. Eventually, all patients were managed by diet alone. Seven patients demonstrated nondiabetic glucose tolerance tests (GTT). Several patients underwent stressful situations after "recovery" without recurrence of hyperglycemia. Glucose-stimulated C-peptide levels were determined postrecovery. C-peptide secretion was in the normal range and, in fact, was identical, in relation to glucose levels, to that in a group of nondiabetic volunteers. In 6 of the 11 cases, C-peptide secretion was measured at the time of initial presentation. These levels were markedly lower than comparable values during the GTT postrecovery. Non-insulin-dependent diabetes, even when presenting in a decompensated state, is subject to a considerable degree of reversibility and even recovery to a nondiabetic state in some cases. Recovery is associated with a return to normal C-peptide secretion.

Efficacy of instant glucose

To the Editor.— Gunning and Garber have shown in their article "Bioactivity of Instant Glucose: Failure of Absorption Through Oral Mucosa" (240:1611, 1978) that buccal absorption of glucose from instant glucose did not occur in normal, nondiabetic volunteers, but that 88% of a swallowed dose of instant glucose was absorbed by intestinal hydrolysis during a 30-minute interval in the same volunteers. They then stated that patients in hypoglycemic coma might possibly have a depressed gag reflex and either aspirate the instant glucose or puddle it in the oropharynx. They therefore conclude that instant glucose may be dangerous or may not work under certain circumstances, and they suggest that "other treatment may be more appropriate." The Diabetes Association of Greater Cleveland has produced and distributed instant glucose since 1967. It was primarily designed for the patient to carry on his person. If the patient feels impending hypoglycemia or friends note unusual

Efficacy of Instant Glucose

To the Editor.— Gunning and Garber have shown in their article Bioactivity of Instant Glucose: Failure of Absorption Through Oral Mucosa (240:1611, 1978) that buccal absorption of glucose from instant glucose did not occur in normal, nondiabetic volunteers, but that 88% of a swallowed dose of instant glucose was absorbed by intestinal hydrolysis during a 30-minute interval in the same volunteers. They then stated that patients in hypoglycemic coma might possibly have a depressed gag reflex and either aspirate the instant glucose or puddle it in the oropharynx. They therefore conclude that instant glucose may be dangerous or may not work under certain circumstances, and they suggest that other treatment may be more appropriate. The Diabetes Association of Greater Cleveland has produced and distributed instant glucose since 1967. It was primarily designed for the patient to carry on his person. If the patient feels impending hypoglycemia or friends note unusual

Carbohydrate tolerance in the very aged

Fifty-three elderly non-diabetic volunteers aged 85 to 96 years were studied when they had reached their pre-admission health state before their discharge from the acute assessment wards of a Geriatric Unit. Blood sugar levels and their corresponding plasma insulin levels were estimated after a 50 g glucose load. Thirty-four patients had normal curves, thirteen had an abnormal 2h. Blood sugar over 120 mg/100 ml and six (all women) had two or more abnormal levels. Carbohydrate intolerance was not related to age, obesity or a positive family history. The results were compared to two groups of young controls, viz nineteen healthy post partum women mean age 29.9 yrs, and twenty-one healthy women mean age 52 years, admitted for investigation of post menopausal bleeding. With increasing age, the peak levels of glucose and insulin are delayed and when carbohydrate intolerance develops the rate of insulin secretion remains the same. The glucose and insulin values closely follow each other and there is no suggestion that insulin secretion is reduced with age. In fact the elderly diabetic shows increased insulin secretion suggesting insulin antagonism or inactivity unrelated to obesity.

Influence of adrenergic receptor stimulation on glucose metabolism during starvation in man: Effects on circulating levels of insulin growth hormone and free fatty acids

Three days of starvation in 23 healthy, non-diabetic volunteers produced a “diabetic-like” state characterized by ketonuria, glucose intolerance, and diminished insulin secretion in response to i.v. glucose. The serum concentration of growth hormone and free fatty acids, and the urinary excretion of free catecholamines were also elevated. Free plasma cortisol remained unchanged. To investigate the influence of adrnergic receptor stimulation on these metabolic alterations, fasting subjects were divided into three groups, 40 min before an i.v. glucose tolerance test (IVGTT). One group received a saline infusion and served as controls. A second group (α-adrenergic blockade) received an infusion of phentolamine beginning 40 min before and lasting throughout the fasting IVGTT; the third group received phentolamine and propranolol (total adrenergic blockade). All subjects were glucose intolerant after fasting, and by comparison with the prefasting IVGTT, it was found that adrenergic blockade had no effect on the change in glucose tolerance after starvation. Control subjects exhibited a 45% ( p < .03) decline in glucose-stimulated insulin secretion, while subjects under α blockade exhibited a 110% increase ( p < .03) in insulin secretion. Subjects under total adrenergic blockade showed a modest decline that was not statistically significant ( p > .30). Alpha adrenergic blockade returned growth hormone levels to prefasting values in three subjects, and total blockade partially restored the free fatty acid concentration to prefasting levels. These results indicate that sympathetic tone, as reflected by catecholamine excretion, is increased during starvation and may play a role in the regulation of insulin, growth hormone, and free fatty acid release; that acute reversal of insulin deficiency after fasting does not restore normal glucose tolerance; and that peripheral insulin antagonism due to growth hormone and free fatty acids does not appear to be a major cause of glucose intolerance during starvation.