Distribution of type II diabetes in nuclear families.

Type II diabetes has a substantial genetic component, but the mode of inheritance and the molecular basis of this inheritance are uncertain. This study documents the familial distribution of the disease in the parents and siblings of a consecutive series of type II diabetic subjects. We studied 66 first-degree relatives of 20 white subjects with type II diabetes and both parents alive. They were tested with a continuous infusion of glucose (5 mg.kg IBW-1.min-1) (n = 49) or FPG and hemoglobin A1c (n = 17). Seven probands had neither parent affected with diabetes or IGT, 10 had one parent affected (6 with diabetes and 4 with IGT), and 3 had both parents affected. The probands with affected and those with unaffected parents were phenotypically similar. These findings indicate that a sizable subgroup of type II diabetic subjects may have neither parent affected with a demonstrable abnormality of glucose tolerance. The assumption of autosomal dominance with complete penetrance is not supported, although it remains possible that a dominant gene of low penetrance may play a role in some pedigrees. Polygenic inheritance would appear likely, and genetic heterogeneity may occur. The inheritance of diabetic traits from phenotypically normal parents needs to be considered in the analysis of genetic linkage with type II diabetes.

Vibration sensory thresholds depend on pressure of applied stimulus.

Vibration sensory thresholds (VSTs) were estimated in 40 healthy subjects and 8 with diabetic peripheral neuropathy. A vibrameter and a biothesiometer were used at four sites and at differing pressures. In normal subjects, with the vibrameter at 200 g, mean VST +/- SE for all sites was 1.87 micron +/- 0.22 and at 400 g dropped to 1.08 micron +/- 0.15 (P less than .0001). In 20 of these subjects with a biothesiometer at 200 and 400 g, mean VST fell from 12.8 +/- 1.5 to 11.1 +/- 1.1 (arbitrary units) (P = .01) when the greater pressure was applied. In the 8 subjects with peripheral neuropathy, with the vibrameter at 200 and 400 g, respectively, mean VST fell from 70.7 +/- 26 to 7.2 +/- 1.8. VST in these subjects was estimated again after 1 mo and showed strong correlations with the previous values. Biothesiometer results correlated with vibrameter results at all sites. Thus, VST decreases as the pressure of the applied stimulus is increased and this effect appears to be more marked in peripheral neuropathy. This has important consequences in monitoring this condition.

Acetate tolerance and the kinetics of acetate utilization in diabetic and nondiabetic subjects.

We investigated acetate utilization in humans by randomly intravenously infusing acetate (2.5 mmol/min) or bicarbonate (2.8 mmol/min) over 60 min into nine nondiabetic and six non-insulin-dependent diabetic subjects followed with or without bolus intravenous glucose (20 g/m2 body surface area). The acetate metabolic clearance rate (MCR) was greater in the nondiabetic subjects (50.4 +/- 14.9 vs 25.0 +/- 6.5 mL.min-1.kg-1, p less than 0.01) as were acetate elimination rate constant (Kac) (0.031 +/- 0.003 vs 0.026 +/- 0.004/min, p less than 0.01) and basal turnover rate (8.56 +/- 3.65 vs 4.92 +/- 1.03 mumol.min-1.kg-1, p less than 0.01); acetate half-time was thus shorter in the nondiabetics (22.6 +/- 2.2 vs 27.2 +/- 3.8 min, p less than 0.01). Kac was reduced and half-time was prolonged in all the subjects (p less than 0.001) when glucose was available. Prior acetate or bicarbonate infusion had no influence on either the KG rate constant of glucose elimination or the postglucose insulin responses in both subject groups. These results suggest that the infused acetate did not worsen glucose tolerance, glucose impaired acetate utilization unlike reported in ruminants, and acetate is rapidly metabolized in humans although at a slower rate in diabetics.

Diabetic diets: high carbohydrate combined with high fiber.

The ideal level of carbohydrate intake for diabetics placed on high-fiber diets is unknown. Nineteen diabetics, therefore, took part in a total of twenty-four 5-day studies of fiber supplementation (guar) with carbohydrate intakes ranging from 22 to 61% of total calories. Where carbohydrate formed more than 40% of the calorie intake, there was a mean 64% reduction in glycosuria over the last 2 days on guar (P < 0.001, 14 studies, 11 patients). No significant reduction in glycosuria was seen in the 10 studies on lower carbohydrate intakes. This suggests that dietary fiber supplements in diabetes should be given against a background of higher rather than lower carbohydrate intake.

Direct animal and indirect human evidence of altered platelet function in diabetics.

All agree on altered platelet function in vitro (and increasingly in vivo) in diabetics of substantial duration and/or with clinical evidence of angiopathy. However, a platelet abnormality earlier in the disease remains uncertain. Three sets of data from Oxford will be reviewed: (1) Observations of Honour on platelet aggregation at sites of minimal injury within blood vessels of anesthetized rabbits, with greater sensitivity to superfused ADP when hyperglycemia has followed alloxan only days previously. This increased aggregatability (not hyperglycemia determined) is reversed by a few days of insulin treatment or by dipyrimadole (alone or with synergistic acetyl salicylic acid): (2) Beta-thromboglobulin is released from platelets and is increased in venesected blood from diabetics after a standardized procedure (no prostaglandin E1 in anticoagulant) with final radioimmunoassay. Results in diabetics after surgery, etc., will also be presented, and (3) in a prospective study of newly-diagnosed, mostly maturity-onset type diabetics, an increase in plasma fibrinogen (thrombin coagulation of plasma, controlled against normals) was observed during the first 3 yr, largely due to males treated with sulfonylureas; decreases in platelet count and in prothrombin concentration were also statistically significant.

The effects of changes in plasma nonesterified fatty acid levels on oxidative metabolism during moderate exercise in patients with non-insulin-dependent diabetes mellitus.

Blood levels of intermediary metabolites were measured and indirect calorimetry was performed in 10 otherwise healthy, non-insulin-dependent diabetic (NIDDM) patients before, during, and after 30 minutes of moderate exercise on three occasions in random order at weekly intervals with (1) heparin treatment to increase preexercise plasma nonesterified fatty acid (NEFA) levels (HEPARIN); (2) acipimox, a nicotinic acid analogue, to reduce preexercise plasma NEFA levels (ACIPIMOX); and (3) no manipulation of preexercise plasma NEFA levels (NIL). With ACIPIMOX, preexercise blood levels were significantly reduced for NEFAs and glycerol (P < .01) and marginally reduced for acetoacetate and 3-hydroxybutyrate (NS) compared with preexercise levels for the other two treatments; these low levels seen with acipimox treatment increased only slightly during exercise and the postexercise period. Plasma NEFA levels increased by approximately 150% (P < .001) with HEPARIN at the same times. The levels of ketone bodies during either NIL or HEPARIN increased rapidly postexercise by approximately 90% to 110% for both acetoacetate and 3-hydroxybutyrate (both P < .01). Plasma insulin levels tended to be lowest (despite similar plasma glucose levels during the three treatments) with ACIPIMOX, while growth hormone (hGH) and, perhaps, noradrenaline levels were highest both during and after exercise. The respiratory quotient (RQ) was highest with ACIPIMOX (P < .05 for exercise and postexercise periods compared with the other two treatments), which, compared with NIL, reduced fat oxidation by 27% and 60% and increased carbohydrate oxidation by 29% and 74% during and after exercise, respectively (all P < .05). These changes in substrate oxidation due to ACIPIMOX were almost opposite to those observed with HEPARIN.(ABSTRACT TRUNCATED AT 250 WORDS)

Arteriovenous differences across human adipose and forearm tissues after overnight fast.

Measurements of arteriovenous differences across subcutaneous abdominal tissue (mainly adipose) and deep forearm tissue (mainly muscle) were made on 25 occasions in normal subjects after an overnight fast. Adipose tissue was shown to be strongly lipolytic (releasing nonesterified fatty acids and glycerol), to clear circulating triacylglycerol, glucose, ketone bodies and acetate, and to produce lactate. Uptake of circulating carbohydrate and ketones was sufficient to account for only 51% of the adipose tissue oxygen consumption, implying that adipose tissue utilizes fuel(s) stored within it. The mean fractional re-esterification rate of fatty acids in adipose tissue was 13% to 19%. Arteriovenous differences were converted to fluxes of carbon atoms to compare the movements of different fuels. (Amino acids were not included in these calculations.) Adipose tissue after an overnight fast was a net exporter of carbon, whereas in resting muscle the uptake of carbon atoms from circulating carbohydrate and lipid fuels approximately balanced the CO2 production. Fatty acids were the main form in which carbon left adipose tissue, and the main source of carbon atoms entering the resting forearm.

Insulin deficiency and insulin resistance interaction in diabetes: estimation of their relative contribution by feedback analysis from basal plasma insulin and glucose concentrations.

The liver and beta cells function in a negative feedback loop, which appears to have a predominant role in regulating both the basal plasma glucose and insulin concentrations. The degree of basal hyperglycemia in diabetes probably provides a bioassay of both the effect of a reduction in insulin secretory capacity and the degree of insulin resistance. A mathematic model of the interaction of insulin deficiency and insulin resistance has been constructed, based on the known response characteristics of the beta cells to glucose, and of plasma glucose and insulin control of hepatic and peripherpal glucose flux. The degree to which beta cell deficiency increases basal plasma glucose reflects the hyperbolic shape of the normal insulin secretory response to different glucose concentrations. The height of basal plasma insulin is a function of the degree of insulin resistance. From the basal plasma insulin and glucose concentrations, the model provides an estimate of the degree to which both beta cell deficiency and insulin resistance contribute to diabetes. The predictions arising from the model are in accord with experimental data in man and in animals. In normal-weight diabetics who do not have increased insulin resistance, the model predicts that more than 85% of beta cell function has to be lost for the basal plasma glucose to rise to 6 mmol/liter, but a further 5%--10% loss increases the basal plasma glucose to over 10 mmol/liter. In a third of a consecutive series of 65 newly presenting, uncomplicated diabetics, both normal weight and obese, the analysis from the model suggested that insulin resistance, rather than beta cell deficit, was the predominant feature.

Influence of moderate physical exercise on insulin-mediated and non-insulin-mediated glucose uptake in healthy subjects.

To establish the relative importance of insulin sensitivity and glucose effectiveness during exercise using Bergman's minimal model, 12 nontrained healthy subjects were studied at rest and during 95 minutes of moderate exercise (50% maximum oxygen consumption [VO2max]). Each subject underwent two frequently sampled intravenous glucose tolerance tests (FSIGTs) for 90 minutes, at rest (FSIGTr) and during exercise (FSIGTe). Plasma glucose, insulin, and C-peptide were determined. Insulin sensitivity (S(I)), glucose effectiveness at basal insulin (S(G)), insulin action [X(t)], and first-phase (phi1) and second-phase (phi2) beta-cell responsiveness to glucose were estimated using both minimal models of glucose disposal (MMg) and insulin kinetics (MMi). Glucose effectiveness at zero insulin (GEZI), glucose tolerance index (K(G)), and the area under the insulin curve (AUC(0-90)) were also calculated. Intravenous glucose tolerance improved significantly during physical exercise. During exercise, S(I) (FSIGTr v FSIGTe: 8.5 +/- 1.0 v 25.5 +/- 7.2 x 10(-5) x min(-1) [pmol x L(-1)]-1, P < .01), S(G) (0.195 +/- 0.03 v 0.283 +/- 0.03 x 10(-1) x min(-1), P < .05), and GEZI (0.190 +/- 0.03 v 0.269 +/- 0.04 x 10(-1) x min(-1), P < .05) increased; however, no changes in phi1 and phi2 were found. Despite a significant decrease in the insulin response to glucose (AUC0-90, 21,000 +/- 2,008 v 14,340 +/- 2,596 pmol x L(-1) x min, P < .01), insulin action [X(t)] was significantly higher during the FSIGTe. These results show that physical exercise improves mainly insulin sensitivity, and to a lesser degree, glucose effectiveness. During exercise, the insulin response to glucose was lower than at rest, but beta-cell responsiveness to glucose did not change.

Ketosis resistance in fibrocalculous pancreatic diabetes: II. Hepatic ketogenesis after oral medium-chain triglycerides.

A majority of patients with fibrocalculous pancreatic diabetes (FCPD) do not become ketotic even in adverse conditions. It is not clear whether this ketosis resistance is due to reduced fatty acid release from adipose tissue or to impaired hepatic ketogenesis. We tested hepatic ketogenesis in FCPD patients using a ketogenic challenge of oral medium-chain triglycerides (MCTs) and compared it with that in matched insulin-dependent diabetes mellitus (IDDM) patients and healthy controls. After oral MCTs, FCPD patients showed only a mild increase in blood 3-hydroxybutyrate (3-HB) concentrations (median: fasting, 0.13 mmol/L; peak, 0.52) compared with IDDM patients (fasting, 0.44; peak, 3.39) and controls (fasting, 0.04; peak, 0.75). Plasma nonesterified fatty acid (NEFA) concentrations were comparable in the two diabetic groups (FCPD: fasting, 0.50 mmol/L; peak, 0.79; IDDM: fasting, 0.91; peak, 1.04). Plasma C-peptide concentrations were low and comparable in the two diabetic groups. Plasma glucagon concentrations were higher in IDDM patients in the fasting state, but declined to levels comparable to those in FCPD patients after oral MCTs. Plasma carnitine concentrations were comparable in the two groups of patients. It is concluded that the failure to stimulate ketogenesis under these conditions could be partly due to inhibition of a step beyond fatty acid entry into the mitochondria.

Adipose tissue metabolism in obesity: lipase action in vivo before and after a mixed meal.

Physiological actions of insulin include suppression of fat mobilization from adipose tissue and activation of adipose tissue lipoprotein lipase. Here, we report measurements of adipose tissue hormone-sensitive lipase (HSL) and lipoprotein lipase (LPL) action in vivo in 10 normal and eight obese subjects, with the latter group having varying degrees of glucose intolerance. HSL and LPL actions (per gram of adipose tissue) were similar in the two groups, after an overnight fast. In the normal subjects, HSL action was suppressed after a meal (by 75% +/- 6% between 60 to 300 minutes, P less than .01), and the action of LPL was increased (clearance of circulating triacylglycerol [TAG] increased by 140% +/- 57% at 300 minutes, P less than .05). Despite hyperinsulinemia, these responses were blunted in the obese subjects (P less than .05 for each change being less than in normal group). The adipose tissue of the obese subjects showed continued nonesterified fatty acid (NEFA) release at a time when NEFA mobilization was completely suppressed in the normal group. Both impaired suppression of HSL and low fractional retention of fatty acids for reesterification within the adipose tissue contributed to this abnormal NEFA release. Impaired activation of LPL was associated with a greater absolute increase in plasma TAG concentration postprandially in the obese. In obese subjects, adipose tissue HSL and LPL fail to respond to immunoreactive insulin postprandially, which may be an important maladaptation in terms of lipoprotein metabolism and risk of coronary heart disease.

Factors controlling fat mobilization from human subcutaneous adipose tissue during exercise.

To investigate possible factors that limit fat utilization during exercise, arteriovenous differences of plasma nonesterified fatty acids (NEFA) and glycerol were measured across the subcutaneous adipose tissue of the anterior abdominal wall in nine subjects who exercised for 60 min at 50-70% of their maximal O2 consumption. The large gradient of NEFA concentration from adipose tissue venous to arterial plasma increased throughout the exercise period. Maximal plasma NEFA concentrations in adipose venous drainage were reached postexercise (median 3,800 mumol/l), with a median NEFA-to-albumin molar ratio of 5.7. Fractional reesterification of fatty acids within the tissue (assessed from the ratio of NEFA to glycerol release) was 20-30% in the basal state and declined during exercise. After exercise there was apparently negative reesterification, implying release of NEFA retained in adipose tissue during exercise. Although these findings challenge current views on the regulation of NEFA release, they are in agreement with the concept of supply of fatty acids from adipose tissue as the major factor limiting fat oxidation during sustained exercise.

The relationship of plasma acetate with glucose and other blood intermediary metabolites in non-diabetic and diabetic subjects.

In investigating the interrelations of plasma acetate with glucose metabolism, we established that fasting plasma acetate levels (mmol/l) were greater in the diabetic than non-diabetic individuals (p less than 0.001). Plasma acetate and glucose levels correlated in all subjects (non-diabetic and diabetic) as a whole (rs 0.28, p less than 0.0001) and in the diabetics alone (rs 0.35, p less than 0.001). After i.v. glucose (20 g/m2 body surface area), plasma acetate levels increased further in the diabetic and non-diabetic individuals. Plasma acetate also increased when non-diabetic individuals consumed 75 g oral glucose. Moreover, while plasma acetate levels had returned to fasting values by 90 min in the non-diabetic subjects after oral and i.v. glucose, levels remained elevated in the diabetics after i.v. glucose. The K rate constant of glucose elimination after i.v. glucose in the diabetics correlated negatively with acetate values at many time points. In the non-diabetics, changing acetate and glucose levels after oral glucose also correlated at multiple time points. These results suggest that the plasma acetate level is influenced by variations in glycaemia and provide further evidence for an impaired rate of acetate metabolism in diabetes.

Polyunsaturated fatty acids and diabetic retinopathy.

One hundred and forty nine diabetic patients were ophthalmologically assessed seven years after randomisation to a low carbohydrate or modified fat diet (rich in linoleic acid). Glycaemic control, regardless of the type of diet, was a major determinant of the development of retinopathy. Poorly controlled patients (haemoglobin A1c greater than 8%) with low levels of linoleic acid in cholesterol ester had a significantly greater frequency of retinopathy than well controlled patients or patients with similarly unsatisfactory control but higher levels of linoleic acid. The findings support an earlier suggestion that linoleic acid might protect against diabetic retinopathy.

The ketosis-resistance in fibro-calculous-pancreatic-diabetes. 1. Clinical observations and endocrine-metabolic measurements during oral glucose tolerance test.

We measured circulating levels of C-peptide, pancreatic glucagon, cortisol, growth hormone and metabolites (glucose, non-esterified fatty acids, glycerol and 3-hydroxybutyrate) in fibro-calculous-pancreatic diabetic (FCPD, n = 28), insulin-dependent diabetic (IDDM, n = 28) and non-diabetic control (n = 27) subjects during an oral glucose tolerance test. There was no difference in the two diabetic groups in age (FCPD 24 +/- 2, IDDM 21 +/- 2 years, mean +/- SEM), BMI (FCPD 16.0 +/- 0.6, IDDM 15.7 +/- 0.4 kg/m2), triceps skinfold thickness (FCPD 8 +/- 1, IDDM 7 +/- 1 mm), glycaemic status (fasting plasma glucose, FCPD 12.5 +/- 1.5, IDDM 14.5 +/- 1.2 mmol/l), fasting plasma C-peptide (FCPD 0.13 +/- 0.03, IDDM 0.08 +/- 0.01 nmol/l), peak plasma C-peptide during OGTT (FCPD 0.36 +/- 0.10, IDDM 0.08 +/- 0.03 nmol/l) and fasting plasma glucagon (FCPD 35 +/- 4, IDDM 37 +/- 4 ng/l). FCPD patients, however, showed lower circulating concentrations of non-esterified fatty acids (0.73 +/- 0.11 mmol/l), glycerol (0.11 +/- 0.02 mmol/l) and 3-hydroxybutyrate (0.15 +/- 0.03 mmol/l) compared to IDDM patients (1.13 +/- 0.14, 0.25 +/- 0.05 and 0.29 +/- 0.08 mmol/l, respectively). This could be due to enhanced sensitivity of adipose tissue lipolysis to the suppressive action of circulating insulin and possibly also to insensitivity of hepatic ketogenesis to glucagon. Our results also demonstrate preservation of alpha-cell function in FCPD patients when beta-cell function is severely diminished, suggesting a more selective beta-cell dysfunction or destruction than hitherto believed.

The measurement of plasma acetate by a manual or automated technique in diabetic and non-diabetic subjects.

A method is described for the measurement of acetate in plasma by an enzymatic technique using acetate kinase, either manually or with the Multistat centrifugal analyser. The technique was used to compare concentrations in diabetic and non-diabetic subjects and to determine correlates with other intermediary metabolites.

Breath hydrogen excretion or plasma acetate levels during the lactulose tolerance test?

Since both acetate and hydrogen are produced by colonic bacterial fermentation, the clinical utility of the measurement of either parameter in nine subjects for the lactulose tolerance test was tested. The fasting plasma acetate concentration (mean +/- s.d., mmol/l) of 0.11 +/- 0.06 increased to peak levels between 150 min (0.23 +/- 0.12) and 180 min (0.23 +/- 0.09), both P less than 0.01, after ingesting 20 g lactulose. In one subject with previous gastrectomy and intestinal hurry, the peak was at 30 min. Mean post-lactulose acetate levels (0.21 +/- 0.09) were higher than fasting levels (P less than 0.03). Breath hydrogen excretion exhibited a similar trend. Indeed, a significant correlation (rs 0.39, P less than 0.01) was demonstrated between the acetate and hydrogen values. It is therefore concluded that patients for the lactulose breath test show fairly similar changes in plasma acetate and breath hydrogen excretion after lactulose ingestion. Either measurement could thus be used in assessing colonic fermentation in humans.

The formation of acetate from ethanol with and without prior chlorpropamide intake in diabetic and non-diabetic subjects.

It has been suggested that raised post-ethanol plasma acetaldehyde levels, from inhibition of aldehyde dehydrogenase, underlie the liability to chlorpropamide, alcohol flushing (CPAF). We tested the hypothesis that acetate formation from acetaldehyde, the reaction catalysed by that enzyme, was also likely to be affected by chlorpropamide (CP) medication. In six healthy non-diabetic 'non-flushers', fasting acetate (Ac +/- s.d. mmol/l) was 0.22 +/- 0.12, and increased by 0.47 +/- 0.14 to peak levels by 30 min after intake of 40 ml dry sherry, which increased plasma ethanol (mmol/l) levels to 10.2 +/- 6.0. After 5 days of CP (250 mg daily), fasting Ac (0.17 +/- 0.05) and increase to peak of Ac and ethanol after 40 ml sherry (0.56 +/- 0.12 and 8.9 +/- 7.2 respectively), were not changed (P n.s.). There was no correlation between Ac and ethanol at any time point. When the studies were repeated in five non-insulin-dependent diabetic 'flushers', both on regular CP medication and after 3 days without CP, there was again no significant difference in fasting and post-ethanol Ac levels between the two studies (fasting 0.18 +/- 0.04 v. 0.17 +/- 0.02, and increase to peak 0.62 +/- 0.13 v. 0.72 +/- 0.18, P n.s.). These results indicate that the conversion of ethanol to acetate is unaffected by CP medication, and furthermore that post-ethanol acetate levels do not predict liability to CPAF.

High-carbohydrate and fibre diets in the treatment of diabetes.

After Kinsell and collaborators (1970) demonstrated a smaller glycaemic rise in diabetic subjects given larger rather than smaller nutrient loads (because of the more complicated composition of the intakes) notions that one can usefully prescribe diabetic diets from crude chemical composition of foods 'on the shelf' have been abandoned, with greater consideration of the varied gastro-intestinal handling of foods, how they are changed by cooking, etc., the way different food interact within the gastro-intestinal tract, and the importance of specific chemical constitution, both of the classical nutrients as well as fibre contents. In practice, high-carbohydrate diets are usually entwined with high-fibre intake. Apart from the observations on the practicability of high-carbohydrate diets in obtaining successful glycaemic control of diabetics outside the 'First World', doubts were voiced in the late 1920s concerning the wisdom of the high-fat intake accompanying low-carbohydrate diets. In the next decade Himsworth showed in normal subjects that high-carbohydrate intake improved glucose tolerance, and this has been repeated in Seattle. Data concerning complete meals or, much better, dietary regimes persisted with over long periods of time are more relevant than those from single intakes of liquid homogenates. We present observations on 6-week intakes of particular dietary regimes (in free-living patients) from which the main conclusions would seem: a high-carbohydrate intake does no harm to glycaemic control in diabetics, providing it is predominantly of polysaccharides; a high-fibre intake has various beneficial effects, and in particular high viscous fibre intake reduces post-prandial glycaemia.(ABSTRACT TRUNCATED AT 250 WORDS)