[Fatty acid composition of serum phospholipids and the effect of insulin in patients with type 2 diabetes]

BACKGROUND

A direct relation has been found between the insulin sensitivity and fatty acid (FA) composition of serum and tissue lipids in adult humans. The aim of our study was to confirm the above relation in different groups of type 2 diabetic patients (DM2).

METHODS AND RESULTS

The FA composition of serum phospholipids was measured by gas liquid chromatography at the insulin action during the two-step hyperinsulinemic isoglycemic clamp (1 and 10 mU/kg.min) in a group of 21 newly diagnosed DM2 subjects (DMN) and in 24 healthy controls (HC). The DMN group consisted of a subgroup of patients treated with hypoglycemic agents (DMH; n = 21) and a group treated with the diet only (DMD; n = 11). In diabetics, the metabolic clearance rates of glucose at either insulin level (MCRglusubmax and MCRglumax) were significantly reduced in comparison with HS (MCRglusubmax--DMN: 5.35 +/- 2.7 ml.kg-1.min-1; DMH: 5.38 +/- 2.17 ml.kg-1.min-1; DMD: 5.48 +/- 2.35 ml.kg-1.min-1; HS: 10.9 +/- 3.3 ml.kg-1.min-1; p < 0.01; and MCRglumax--DMN: 13.3 +/- 3.3 ml.kg-1.min-1; DMH: 12.5 +/- 3.0 ml.kg-1.min-1; DMD: 13.3 +/- 3.0 ml.kg-1.min-1; HS: 17.4 +/- 3.8 ml.kg-1.min-1; p < 0.05). An increased content of highly unsaturated n-6 family FA (p < 0.01), especially of the arachidonic acid (DMN: 10.98 +/- 1.79%; DMD: 10.78 +/- 1.64%; DMH: 10.97 +/- 1.70% vs HS: 8.51 +/- 1.53% (p < 0.01) was found in all groups of diabetics compared to HS, and lower levels of linoleic acid in DMN (p < 0.001), and DMH (p < 0.05) were identified. The content of saturated FA and that of monosaturated FA was comparable in HS, DMN and DMD persons. While in healthy subjects a negative correlation between MCRglu and the content of saturated FA as well as a positive association between insulin action and the ration of linoleic and arachinonic acids were found, no such relation was found in the diabetic subjects.

CONCLUSIONS

Different groups type 2 diabetic patients show altered FA pattern of serum phospholipids. Changes in FA composition may play a role in the modulation of insulin action in peripheral tissues, but they cannot explain the insulin resistance in type 2 diabetic patients.

Serum phospholipid fatty acid composition and insulin action in type 2 diabetic patients

Relationships have been demonstrated between insulin sensitivity and the fatty acid (FA) composition of serum and tissue lipids in adult humans. The present study aimed to investigate the above relationships in different groups of type 2 diabetic patients (DM2). The FA composition of serum phospholipids (S-PL) measured by gas liquid chromatography and insulin action during a 2-step hyperinsulinemic isoglycemic clamp (1 and 10 mU/kg. min) were determined in 21 newly diagnosed DM2 subjects (DMN), in groups of long-term DM2 patients treated with hypoglycemic agents (DMH; n = 21) or diet alone (DMD; n = 11), and in 24 healthy subjects (HS). In diabetics, the metabolic clearance rates of glucose at both insulin levels (MCR(glu)submax and MCR(glu)max) were significantly reduced compared with HS (MCR(glu)submax DMN, 5.35 +/- 2.7 mL x kg(-1) x min(-1), DMH, 5.38 +/- 2.17 mL x kg(-1) x min(-1); DMD, 5.48 +/- 2.35 mL x kg(-1) x min(-1) v HS, 10.9 +/- 3.3 mL x kg(-1) x min(-1); P <.01; MCR(glu)max DMN, 13.3 +/- 3.3 mL x kg(-1) x min(-1); DMH, 12.5 +/- 3.0 mL x kg(-1) x min(-1); DMD, 13.3 +/- 3.0 mL x kg(-1) x min(-1) v HS, 17.4 +/- 3.8 mL x kg(-1) x min(-1); P <.05). Increased contents of highly unsaturated n-6 family FA (P <.01), arachidonic acid in particular (DMN, 10.98% +/- 1.79%; DMD, 10.78% +/- 1.64%; DMH, 10.97% +/- 1.7% v HS, 8.51% +/- 1.53%; P <.001), were found in all groups of diabetics compared with HS, while lower levels of linoleic acid were seen in DMN (P <.001) and DMH (P <.05). The contents of saturated FA and monounsaturated FA were comparable in HS, DMN, and DMD. While in HS there were significant negative correlations between MCR(glu) and the contents of saturated FA and a positive association between insulin action and proportions of linoleic and arachidonic acids, no significant relationships were found in diabetic subjects. Different groups of DM2 patients show an altered FA pattern of S-PL, which is not related to insulin action. The above data support the hypothesis that changes in FA composition may play a role in modulating insulin action in peripheral tissues, but cannot explain the insulin resistance (IR) in DM2 patients.

[Treatment of diabetes with the insulin pump]

Diabetes control by subcutaneous insulin infusion (CSII) by an insulin pump becomes the therapeutic option, which most closely mimics the physiologic insulin secretion pattern. It may bring glycemia close to normal levels even in cases where the standard injection insulin therapy fails. After CSII installation the mean daily dose of insulin can be reduced and the compensation of diabetes improves (decreases). CSII is usually installed in diabetic patients where the disease cannot be sufficiently controlled, namely in patients with "dawn phenomenon", severe hypoglycemia, and progression of diabetic complications. Results of long-term follow-up study of CSII-treated diabetic patients at our department (IKEM) confirmed the high efficacy of this method and the minimal incidence of therapy-related complications (severe hypoglycemia, ketoacidosis, body weight increase, technical complications).

[Autonomic neuropathy in patients with type 2 diabetes and microalbuminuria]

BACKGROUND

Microalbuminuria (MAU) represents in patients with type 2 diabetes a risk factor for total and cardiovascular mortality and morbidity, whose principal pathogenic mechanism is the development of atherosclerosis. Other factors may also participate, e.g., cardiovascular vegetative neuropathy, which is supposed to be an independent risk factor. The aim of the study was the analysis of the cardiovascular autonomic regulations in patients with type 2 diabetes and microalbuminuria.

METHODS AND RESULTS

16 patients with type 2 diabetes and microalbuminuria and 23 healthy controls were included in the study. Heart rate variability was tested (during short-term recording at rest, deep breathing, orthostasis and Valsalva manoeuvre) and spectral analysis of telemetric records of heart rate in three positions (lying--standing--lying) was employed. In the group of patients with type 2 diabetes and MAU, in comparison with patients without MAU and controls, significant differences in heart rate variability during deep breathing were found. In comparison to controls, differences were found also during the Valsalve manoeuvre. In parameters of reaction of the heart rate to orthostasis, both groups of diabetic patients differed from controls. When comparing patients with MAU and controls significant differences were also found in spectral analysis of the heart rate variability, namely in total spectral power and the power of the low frequency band in both recumbent positions. In the same parameters, significant differences were found also between patients with and without MAU. The later were not different from the controls.

CONCLUSIONS

The presented results indicate the existence of a significant impairment of the autonomic nervous system in patients with type 2 diabetes and microalbuminuria. This fact may contribute to the higher cardiovascular risk in this group of diabetic patients.

[Mutation in the beta3-adrenergic receptor gene (Trp64Arg) does not influence insulin resistence, energy metabolism, fat distribution and lipid spectrum in young people. Pilot study]

A missence mutation Trp64Arg in the beta3-adrenergic receptor gene is associated with obesity, insulin resistance, a lower metabolic rate and the earlier onset of NIDDM but the published results are controversial. We investigated the effect of this mutation on insulin resistance (euglycemic hyperinsulinemic clamp), on fat mass and fat distribution (anthropometry, bioimpedance, CT) and resting metabolic rate (indirect calorimetry), lipid spectrum and other metabolic disturbances in Czech juveniles recruited from juvenile hypertensives (H, n = 68) and controls (C, n = 81). The frequency of this mutation (determined by digestion of 210 bp PCR product with MvaI) was double in H than in C (14.7%, vs. 7.4%) and the carriers of Arg64 allele had sig. higher fasting glucose (H: p = 0.002. C: p = 0.025). Four Trp64/Arg64 and six Trp64/Trp64 men (age 23 +/- 4.2, vs. 22.5 +/- 1.9 y, BMI 26 +/- 5.5, vs. 22.9 +/- 5.1 kg/m2) took part in a detailed pilot study. But no signif. differences (Horn's method) in fasting glucose (4.6 +/- 0.6, vs. 4.9 +/- 0.4 mmol/l), in parameters of insulin resistance (M-value150-180 min. 9.1 +/- 1.1, vs. 8.9 +/- 1.5 mg glucose/kg.min(-1)), resting metabolic rate/lean body mass (RMR/kg LBM: 78.6 +/- 4.6, vs. 85.6 +/- 23.2 kJ/kg), lipid spectrum and other screened parameters were found. The lowest resting metabolic rate (RMR/kg LBM 55.4; 62.6 kJ/kg) was found in brothers (both C, Trp64/Trp64) who highly differ in body constitution (BMI 19.0 resp. 32.4 kg/m2). We suppose that in this case the energy metabolism is probably determined by other genetic loci and does not correlate with body fat mass.

CONCLUSION

Our pilot study does not confirm the influence of Trp64Arg mutation in heterozygous carriers on insulin resistance, energy metabolism and lipid spectrum.

Decreased urinary kallikrein with hyperglycemia in patients with short-term insulin-dependent diabetes mellitus

The aim of the study was to evaluate the role of urinary kallikrein in the regulation of renal hemodynamics and sodium handling in insulin-dependent diabetes mellitus (IDDM), and to test the effect of acutely induced hyperglycemia. Urinary kallikrein excretion was evaluated (1) under basal conditions and after stimulation with i.v. furosemide (0.5 mg x kg(-1)), (2) during glycemic clamp-induced eu- and hyperglycemia (5 and 12 mmol/L) and, (3) during time-controlled euglycemia in 21 short-term IDDM patients without microalbuminuria and in 18 weight-, age- and gender-matched healthy controls. Sodium excretion and renal hemodynamics using the clearances of inulin and para-amino-hippuric acid were measured during examinations in both groups. The baseline urinary kallikrein excretion during clamp-induced euglycemia was comparable in diabetic and control subjects (10.89+/-5.98 versus 10.38+/-3.73 mUE x min(-1)), whereas it was decreased in the baseline for furosemide (5.77+/-3.22 versus 10.9+/-3.7 mUE x min(-1); p < 0.01) and even after furosemide administration (12.0+/-1.6 versus 21.3+/-2.0 mUE x min(-1); p < 0.01) while the patients were hyperglycemic. During intravenous dextrose-induced hyperglycemia, the urinary kallikrein excretion significantly declined in diabetic patients (10.89+/-5.98 versus 5.45+/-0.88 mUE x min(-1); p < 0.01), whereas it did not change in controls (10.38+/-3.73 versus 12.55+/-5.47 mUE x min(-1)). A decrease in the fractional excretion of sodium and an attenuated rise in natriuresis after furosemide administration have been found in diabetic compared to control subjects. There were no significant relationships between kallikrein excretion and (1) renal hemodynamics, which was comparable in both groups, or (2) plasma renin activity, plasma and urine aldosterone and cortisol. We conclude that short-term IDDM without renal hemodynamic alterations is associated with decreased basal and furosemide-stimulated kallikrein excretion, which is directly related to the blood glucose level. The decreased activity of the renal kallikrein-kinin system might be involved in the increased tendency to sodium retention in diabetic patients.

[Erythrocyte membrane sodium transport in patients with type I diabetes mellitus (insulin-dependent diabetes mellitus)]

BACKGROUND

Disorders in sodium metabolism such as an increased total body exchangeable sodium, were found in diabetic patients, although the underlying mechanisms were not clear. The aim of the study was to evaluate red blood cell sodium transport in patients with insulin dependent diabetes mellitus (IDDM) without diabetic nephropathy.

METHODS AND RESULTS

Renal hemodynamics using the clearance of inulin and para-amino-hippuric acid during euglycemic clamp and red blood cell sodium transport were examined in 13 IDDM patients without microalbuminuria and in 12 weight-, age- and sex-matched healthy controls. Despite normal renal hemodynamics and intracellular sodium concentrations (6.57 +/- 1.45 vs 5.95 +/- 0.60 mmol/l), IDDM patients had lowered clearance of sodium (2.22 +/_ 1.11 vs 3.24 +/- 1.32 ml/min; p < 0.01) and increased activity of natrium-lithium countertransport compared to C (0.76 +/- 0.50 vs 0.31 +/- 0.22 mmol.l-1 .h-1; p < 0.01). No significant differences between IDDM and C were found in Na+-K+ pump (7.95 +/- 1.95 vs 6.9 +/- 0.99 mmol.l-1 .h-1), in Na+-K+ cotransport (0.68 +/- 0.82 vs 0.82 +/- 0.71 mmol.l-1 .h-1) and in passive Na+ permeability (0.11 +/- 0.05 vs 0.09 +/- 0.02 mmoll.l-1 .h-1).

CONCLUSIONS

IDDM patients without signs of diabetic nephropathy have shown changes in sodium-lithium countertransport which could play a role in the pathogenesis of diabetic nephropathy and hypertension in the course of the disease.

[Renal hemodynamics and its regulation in recently diagnosed type 1 diabetes mellitus (insulin-dependent diabetes mellitus). The effect of hyperglycemia]

BACKGROUND

The changes in renal haemodynamics are considered to be one of the pathophysiological mechanisms of the development of diabetic nephropathy. The aim of the study was to evaluate the renal haemodynamics and its regulation in insulin-dependent diabetes mellitus (IDDM) during glycemic clamp-induced eu- and hyperglycaemia (5 and 12 mmol/l), and to test the hormonal vasoactive systems after stimulation with furosemide.

METHODS AND RESULTS

Renal haemodynamics using the clearances of inulin and paraaminophippuric acid during eu-hyperglycaemic clamp and furosemide test were performed in 21 short-term IDDM patients without microalbuminuria (DM) and in 18 weight-, age- and sex-matched healthy controls (K). The glomerular filtration rate and effective renal plasma flow were comparable in IDDM and C and were not affected by hyperglycaemia. Compared to C diabetics had lowered fractional excretion of sodium (1.41 +/- 0.68 vs 2.23 +/- 0.67%; p < 0.01), which did not change during hyperglycaemia, and lowered furosemide stimulated natriuresis (1242 +/- 339 vs 1606 +/- 340 mumol/min; p < 0.01). Hyperglycaemia resulted in comparable fall in fractional excretion of potassium in both groups (p < 0.001). Decreased basal (5.77 +/- 3.22 vs 10.9 +/- 3.7 mEU/min; p < 0.05) and furosemide-stimulated (12.0 +/- 1.6 vs 21.3 +/- 2.0 mEU/min; p < 0.01) urinary kallikrein has been found in diabetic compared to control subjects. During clamp-induced euglycaemia, kallikrein excretion was comparable in diabetic and control subjects (10.89 +/- 5.98 vs 10.38 +/- 3.73 mEU/min) and significantly declined during intravenous dextrose-induced hyperglycaemia in diabetics (p < 0.01), while it did not change in controls. There were no differences and no changes in plasma renin activity, plasma and urine aldosterone and cortisol in IDDM and C.

CONCLUSIONS

The short-term IDDM without renal haemodynamic alterations is associated with the tendency to sodium retention and decreased basal and furosemide-stimulated kallikrein excretion, which is directly related to the blood glucose level. Acutely-induced hyperglycaemia decreases fractional excretion of potassium, which cannot be explained by the changes of evaluated hormonal systems.

[Relation between serum amino acids and insulin sensitivity (results of a clamp study in offspring of hypertensive patients]

Hypertension which is part of the metabolic syndrome has frequently a family background. The authors investigated therefore indicators of insulin sensitivity by the method of a hyperinsulinaemic euglycaemic clamp in the offspring of hypertensive probands. In conjunction with the increased interest in the role of muscles in influencing insulin sensitivity the authors were also interested in serum amino acid levels. They examined a group of 15 healthy offspring of hypertonic subjects (PHT) and compared them with a group of 18 healthy volunteers without a family-history of hypertension. PHT had as compared with controls a higher systolic pressure (117 +/- 7.2 mm Hg vs. 106.1 +/- 11.7 mm Hg p < 0.01). In the clamp examination in PHT significantly lower indexes of tissue insulin sensitivity were recorded, SI (46.51 +/- 11.8% vs. 54.3 +/- 7.79%, p = 0.02) and ISI (6.6 +/- 3.99 vs. 9.88 +/- 5.05, p < 0.01). In the PHT group were, in addition to the different ratio of some branched chain amino acids and tyrosine, also relations between indicators of insulin sensitivity and arginine. It is thus obvious that signs of reduced insulin sensitivity are present in PHT already in the preclinical stage. Relations between the altered insulin sensitivity and arginine, the precursor of nitrogen oxide, apparent only in PHT could be a stimulus for seeking associations with endothelial damage described in insulin resistant conditions.

Effects of insulin and lipid emulsion on renal haemodynamics and renal sodium handling in IDDM patients

To evaluate the role of insulin and hypertriglyceridaemia in the regulation of renal haemodynamics and sodium handling in insulin-dependent diabetes mellitus (IDDM), 11 IDDM patients without microalbuminuria and 13 weight-, age-, protein intake- and sex-matched healthy control subjects were studied. Clearances of inulin (Cin), para-amino-hippuric acid (CPAH), sodium (CNa), and lithium (CLi) were measured in four 60-min clearance periods (periods I, II, III and IV) during isoinsulinaemia with lipid emulsion infusion (study 1), a hyperinsulinaemic isoglycaemic clamp with Intralipid infusion (study 2), and during time-controlled isoinsulinaemia (study 3). We found that Cin, CPAH and filtration fraction were comparable in IDDM and control subjects, whereas CNa was decreased in diabetic subjects (2.01 +/- 1.11 vs 3.03 +/- 1.32 ml/min; p < 0.05) due to elevations of proximal tubular fractional and absolute reabsorptions of sodium (p < 0.05). Insulin infusion did not affect Cin, increased CPAH (p < 0.05) and, consequently, lowered the filtration fraction (p < 0.01) in both groups. While acute hyperinsulinaemia resulted in increases in distal tubular fractional and absolute reabsorptions of sodium (p < 0.01) contributing to a fall in CNa (p < 0.01) in control subjects, in diabetic subjects the sodium-retaining effect of insulin was not significant. The lipid emulsion did not alter any of the estimated parameters. We conclude that IDDM without microalbuminuria is associated with a tendency to sodium retention which is not aggravated by insulin when compared to control subjects. Acutely induced hypertriglyceridaemia does not alter renal haemodynamics or renal sodium handling.

[Insulin resistance and non-insulin dependent diabetes mellitus]

Normal glucose tolerance depends primarily on 1) the ability of the body to secrete insulin, 2) the normal insulin action in target tissues, it means the ability of insulin to inhibit hepatic glucose production and to promote glucose uptake, 3) and the ability of glucose to enter the cells in the absence of insulin. Clinically overt non-insulin-dependent diabetes mellitus (NIDDM) is characterized by abnormality of insulin secretion combined with insulin resistance in glucose metabolism of all major target tissues. While the fasting hyperglycaemia depends primarily on decreased insulin ability to inhibit hepatic glucose production, in the postabsorptive state the main role is played by decreased insulin-stimulated glucose uptake in muscles and impaired glycogen synthesis. Because of hyperglycaemia, and increased insulin-independent glucose uptake, whole glucose utilisation is not altered in NIDDM. Combination of genetic and environmental factors leading to secondary changes in insulin action, contribute to the pathogenesis of insulin resistance and progression of NIDDM.

[Insulin resistance and insulin secretion in type II non-obese diabetics]

BACKGROUND

Glucose tolerance depends essentially on insulin secretion and its action in target tissues. Diabetes mellitus type II (insulin-nondependent diabetes) is a disease conditioned by a dysbalance between insulin secretion and effect; it has not been decided whether the cause is insulin resistance or impaired insulin secretion, although a defect of insulin secretion for the manifestation of the disease is generally accepted. The purpose of the submitted study was to assess to what extent insulin secretion and its effect after an oral glucose load and a hyperglycaemic clamp is affected in different groups of non-obese patients with diabetes type II.

METHODS AND RESULTS

The authors examined 21 men with diabetes type II (age 41 +/- 2.6 years, BMI 26.2 +/- 3.2, HbA1,c 9.4 +/- 2.9%) in the course of one year after detection of the disease, treated by diet alone. The second group was formed by 20 patients with diabetes type II (age 46.1 +/- 3.6 years, BMI 26.0 +/- 2.1, HbA1,c 6.94 +/- 1.6%) who suffered from diabetes for 5-10 years and who were treated by diet alone. The third group was formed by 32 diabetics type II (age 51.8 +/- 6.1 years, BMI 26.7 +/- 2.2, HbA1,c 8.7 1.2% +/-) who suffered from diabetes for 5-10 years and were treated with oral antidiabetics. The control group was formed by 42 healthy men matched for body weight and age (age 39.9 years, BMI 25.3, blood sugar level 4.8 mmol/l). Although the diabetic groups did not differ in the fasting blood sugar level (8.0-8.29-8.2 mmol/l), the glycosylated haemoglobin HbA1,c level is lowest in the group of diabetics treated by diet alone, similarly as the rise of the blood sugar level 120 mins, following oral administration of 75 g of glucose (10.3 mmol/l, as compared with 16.2 mmol/l and 15.5 mmol/l in the other groups). The authors found in all groups of diabetic patients, as compared with controls, a comparable drop of the insulin effect evaluated as the metabolic glucose clearance during an hyperinsulinaemic euglycaemic (5 mmol/l) or isoglycaemic (fasting blood sugar level) clamp, the insulin level being 75 microU/ml (controls 10.9 +/- 3.3 ml/kg.min., first group 5.35 +/- 2.7 ml/kg.min., second group 5.47 +/- 2.35 ml/kg.min., third group 5.38 +/- 2.1 ml/kg.min. The differences, as compared with controls, were significant in all groups, p < 0.01). At an insulin level of 1500 microU/ml the results are similar (controls 17.4 +/- 3.8 ml/kg.min., as compared with 13.3 +/- 3.3 in the first group, 13.3 +/- 3.0 in the second group and 12.5 +/- 3.0 ml/kg.min. in the third group: statistical significance in all three groups, as compared with controls, is p < 0.05). The authors did not reveal any differences in the specific insulin bond to insulin receptors of erythrocytes. The total glucose consumption during an isoglycaemic clamp in diabetics and a euglycaemic clamp in controls did not differ. In all diabetic groups, as compared with controls, higher C peptide values and insulin values (IRI) were found on fasting and a slower rise and longer persistence of higher levels after oral glucose administration, although an inadequate secretory response during the hyperglycaemic clamp in diabetics is apparent. Hyperinsulinism was significantly higher in the second group. The number of insulin receptors on erythrocytes, the affinity for insulin, regardless whether the receptors were free or occupied, did not differ significantly between groups.

CONCLUSIONS

All investigated groups of type II diabetics had a comparable degree of insulin resistance which did not depend on the duration of diabetes, its compensation or the type of treatment. Although impaired insulin action was proved, the total glucose utilization in relation to hyperglycaemia is not reduced. The differences in the degree of glucose intolerance in the investigated groups of diabetics type II depend on the degree of impairment of insulin secretion.

Metabolic effects of omega-3 fatty acids in type 2 (non-insulin-dependent) diabetic patients

The metabolic effects of a 3-week dietary supplement of a fish oil concentrate was examined in mildly obese, normotriglyceridemic men with non-insulin-dependent diabetes mellitus (NIDDM) treated with hypoglycemic agents (n = 20). Patients were randomized into two groups, receiving 15 ml per day of fish oil (Martens Oil, Norway) containing 3.1 g of omega-3 fatty acids (FA) (n = 10) or placebo (n = 10). Whereas fish oil led to the expected increase in the ratio of omega-3 to omega-6 FA in serum phospholipids, reflecting the increase in omega-3 FA intake, it did not alter fasting or mixed meal stimulated blood glucose, plasma insulin, and C-peptide concentrations. No changes in insulin action were noted, estimated by the metabolic clearance rates of glucose at plasma insulin levels of approximately 100 microU/ml and 1,400 microU/ml during a hyperinsulinemic, isoglycemic clamp; no changes were seen in insulin binding to erythrocytes. We conclude that during short-term administration, no adverse effects of low dose fish oil on glucose homeostasis were found in mildly obese NIDDM patients treated with oral hypoglycemic agents.

[Glucose utilization and risk of hyperglycemia during simultaneous administration of branched-chain amino acids and fat emulsions in healthy persons]

In order to evaluate the effect of substrate competition on glucose utilization, we studied 8 healthy volunteers under three different conditions: 1. Hyperinsulinemic (75 a 550 microU/ml) euglycemic (5 mmol/1) clamp (HEC). 2. HEC with Nutramin VLI infusion given at a rate of 2 ml/kg.h. 3. HEC with infusion of Nutramin VLI (2 ml/kg.h) and Intralipid (0.15 g of fat/kg.h). Glucose utilization was evaluated as the glucose disposal rate during HEC. We have found, that Nutramin VLI given alone or with Intralipid does not significantly decrease glucose utilization at insulinemia of about 75 and 550 microU/ml. We conclude that simultaneous administration of substrates during parenteral nutrition at standard rates does not raise the risk of hyperglycemia in healthy men.

Glucose and fat utilization during intravenous administration of glucose and lipid emulsion in non-insulin-dependent diabetic patients

To evaluate the clinical significance of substrate competition in the insulin-resistant state, we measured glucose and lipid utilization in 10 non-insulin-dependent diabetic patients during an isoglycemic hyperinsulinemic (approximately 75 and approximately 1500 mU/L) clamp without and with the concomitant infusion of Intralipid (0.15 g triglycerides.kg-1 x h-1) and during Intralipid infusion only in combination with indirect calorimetry. We found that a lipid emulsion does not alter the metabolic clearance rates of glucose at insulinemias of approximately 75 mU/L (5.58 +/- 2.56 vs. 6.03 +/- 2.43 ml.kg-1 x min-1) and approximately 1500 mU/L (13.55 +/- 3.17 vs. 13.75 +/- 4.36 ml.kg-1 x min-1) and it does not change oxidative and nonoxidative glucose disposal rates. Insulin and glucose attenuate the Intralipid-induced increase in serum triglycerides, free fatty acids, and lipid oxidation. We conclude that, whereas Intralipid infused at a standard rate does not decrease glucose utilization under hyperinsulinemic conditions, its own removal from the plasma is enhanced by glucose and insulin in non-insulin-dependent diabetic patients.

[The effect of fish oil on the secretion and effect of insulin in patients with type II diabetes]

The metabolic effect of 3-week dietary supplementation with a fish oil concentrate was examined in not markedly obese, not hypertriglyceridemic men with non-insulin-dependent diabetes mellitus (NIDDM) treated with hypoglycemic agents. Ten patients were given 15 ml/d of fish oil (Martens Oil, Norway) equivalent to 3.1 g of n-3 fatty acid (FA) per day, and compared to 10 diabetics treated with placebo (15 ml/d saline). While fish oil leads to expected increase in the ratio of n-3 to n-6 FA intake, it does not alter fasting and mixed meal stimulated blood glucose, plasma insulin and C-peptide concentrations. There were no changes in insulin action estimated by the metabolic clearance rates of glucose at plasma insulin levels of about 100 microU/ml and 1400 microU/ml during hyperinsulinemic isoglycemic clamp, and no changes were seen in insulin binding to erythrocytes. Even though our short-term study does not warrant authoritative conclusions, no adverse effects of low-dose fish oil on glucose homeostasis have been found in not markedly obese NIDDM patients treated with oral hypoglycemics.

Effect of acute hyperinsulinemia on fatty acid composition of serum lipids in non-insulin-dependent diabetics and healthy men

The fatty acid pattern of serum phospholipids, cholesteryl esters, triglycerides and free fatty acids was measured before and after a 5-h two-step euglycemic hyperinsulinemic clamp (75 and 1400 microU/ml) in 21 non-insulin-dependent diabetics and 14 age-, weight-, and sex-matched healthy controls. Acute hyperinsulinemia was associated with a statistically significant increase in essential fatty acid and a decrease in non-essential fatty acid contents in triglycerides while the levels of serum triglycerides and free fatty acids dropped in both groups. The fatty acid composition of phospholipids and cholesteryl esters remained unchanged as did the levels of serum phospholipids, total cholesterol and HDL cholesterol.

Insulin action and insulin binding following pancreas transplantation

Insulin action and insulin specific binding to erythrocytes were examined in ten recipients of a pancreatic segment and renal graft (Group 1), in nine non-diabetic kidney recipients (Group 2) and in ten age- and weight-matched healthy control subjects (Group 3). All transplant recipients were normoglycaemic without need of insulin, received the same immunosuppression and had good renal graft function at 11-18 months post-transplantation, when the investigation was performed. Using the insulin clamp technique, insulin action was expressed as the metabolic clearance rate of glucose at insulin infusion rates of 1.0 (MCRsubmax) and 10.0 (MCRmax) mU.kg-1.min-1. In comparison with the healthy control subjects, fasting free insulin and C-peptide levels were significantly higher in Groups 1 and 2, but no differences between Groups 1 and 2 were found (p greater than 0.05). Mean values +/- SEM of MCRsubmax in Groups 1, 2 and 3 were 6.30 +/- 0.55, 6.09 +/- 0.69 and 10.52 +/- 1.10 ml.kg-1.min-1 respectively, and of MCRmax 12.65 +/- 0.78, 13.14 +/- 0.92 and 19.28 +/- 1.42 ml.kg-1.min-1 respectively. Insulin action was significantly decreased in Groups 1 and 2 at the low as well as the high insulin infusion rates but there was no difference between the two groups of recipients (p greater than 0.05). No differences in binding data (specific binding, number of binding sites per cell) were found. It is concluded that insulin resistance is common to all immunosuppressed organ recipient and is not related to the pancreas graft. The decrease maximal response to insulin and normal insulin binding to erythrocytes tend to suggest a post-receptor defect in insulin action.

Fatty acid composition of serum lipids and erythrocyte membranes in type 2 (non-insulin-dependent) diabetic men

The fatty acid (FA) composition of serum lipids and erythrocytes was studied in 21 men with non-insulin-dependent diabetes mellitus (NIDDM) and in 14 normal subjects matched for age, sex, body weight, and dietary intake. Lower levels of linoleic acid and higher levels of highly unsaturated FA (daughter) of n-3 and n-6 family FA, reflected in a higher unsaturation index, were found in serum phospholipids (S-PL), in phospholipids of erythrocyte membranes (ery-PL), and in serum cholesterolesters (S-CHE). The unsaturation index of serum phospholipids significantly correlated with glycosylated hemoglobin A1c (P less than .05) and blood glucose levels after glucose load (P less than .001). The results suggest that elongation and desaturation of essential FA (linoleic acid in particular) are increased. The above changes may be associated with accelerated atherosclerosis in type 2 diabetics.

[Insulin secretion and insulin resistance in type II diabetes. Relation to fatty acid composition of serum phospholipids]

Non-obese middle-aged men (n = 21) in an early stage after manifestation of Type 2 diabetes mellitus, and free of signs of atherosclerotic complications, when compared with an age-, weight- and sex-matched control group (n = 14), were found to show: 1. a decrease in linoleic acid content and increase in polyunsaturated elongated forms of n-6 and n-3 families fatty acids in serum phospholipids; 2. fasting hyperinsulinemia and impaired dynamics of insulin secretion after glucose load; 3. insulin resistance due to both receptor and postreceptor defect. Under physiologic conditions (i.e., in the control group), the drop in linoleic acid content and the rise in saturated fatty acids were associated with increased insulin secretion, and decrease in maximal insulin action. The nature of the changes in fatty acid pattern, the decrease in linoleic acid in particular, resembles findings made in persons who died middle-aged from serious complications of atherosclerosis. Combined with the relationship between the fatty acid composition of lipids and insulin secretion and action, our findings suggest a common metabolic defect of atherosclerosis and Type 2 diabetes which is probably insulin resistance in glucose metabolism.

[The importance of C-peptide determination in the treatment and prognosis of type II diabetes]

The concentration of C peptide which is an indicator of the secretory capacity of the beta-cells of the pancreas was assessed in 109 patients with type II diabetes, hospitalized on account of prolonged difficulties as regards compensation. The values on fasting, the maximal values after stimulation following an experimental meal and increments were greater than in age- and weight-matched controls. In diabetic patients some highly significant relationships were revealed between the C peptide concentration on fasting and indicators of the risk of ischaemic heart disease [IHD]. They included HDL cholesterol, the body mass index and uric acid. The relationship between the maximal C peptide concentration and serum sodium may be associated with a greater disposition for hypertension. Thirty-one patients with symptoms of an ischaemic myocardial lesion had a significantly elevated C peptide concentration on fasting. The increments of C peptide concentration after an alimentary stimulus correlated indirectly with indicators of the actual and long-term compensation of diabetes. In relation to the reduced increments also the need of insulin therapy was reflected. Data obtained by examination of the C peptide concentration in the blood of type II diabetics can contribute to the objectivization of needs of insulin treatment and to the detection of the link between cardiovascular risk and hyperinulinaemia.

Interrelationship between glucose and fat utilisation during simultaneous IV administration of glucose and lipid emulsion in healthy man

In order to evaluate the interaction between glucose and fat utilisation during parenteral nutrition, we studied 12 healthy volunteers under three different conditions: While Intralipid infusion does not alter the glucose utilisation, measured by metabolic clearance rate of glucose at an insulin level of about 80 uU/ml (MCR(glu)submax) 11.3 +/- 1 v.s. 11.48 +/- 0.9 ml/kg/min) and the sensitivity index, it decreases glucose utilisation at an insulin level of about 550 uU/ml (MCR(glu)max) (17.8 +/- 1.3 v.s. 15.9 +/- 0.9 ml/kg/min, p < 0.05) suggesting postreceptor alterations in insulin action. Simultaneous administration of Intralipid with glucose and insulin is associated with a smaller increase in serum triglycerides than the infusion of Intralipid alone (2.56 +/- 0.4 v.s. 5.44 +/- 0.5 mmol/lm p < 0.001). We conclude that, when infused at standard rates, Intralipid does not decrease glucose utilisation significantly and, at the same time, its own clearance is enhanced by glucose and insulin.

[Hyperglycemia, hyperinsulinism, atherosclerosis]

The paper deals with a group of 117 patients with clearly defined clinical signs of atherosclerosis following myocardial infarction appearing in middle age, analyzes relationship between indicators of saccharide metabolism and cardiovascular morbidity within a ten-year period, and discusses its potential cause. Fasting levels taken at 120 minutes after the administration of glucose and the sum of the fasting level and three stimulated levels of blood sugar, or insulin (IRI), were compared with 54 controls as well as within the group of patients. Compared with the control group, the patients had glycemia levels elevated. In the group of patient with ischaemic heart disease (glycemia levels especially the sum but also glycemias at 120 min.) were elevated in persons with signs of ischaemic disease of lower extremities, with hypertension, in cases with increased serum triacylglyceroles, with increased energy intake (including fasting levels). The sum of insulin kept increasing in cases with familial disposition to atherosclerosis, with clinical progression of atherosclerosis over a period of 5 years (non-fatal reinfarctions). This had a highly significant correlation with linoleic acid in total serum lipids suggesting correlation with cardiovascular morbidity. This finding stresses the necessity of a comprehensive view of deviations in sacharide metabolism, especially as regards the relationship between elevated glycemia and cardiovascular morbidity, and between insulin and mortality-causing factors.

Insulin binding to erythrocytes and fatty acid composition of erythrocyte membrane phospholipids in healthy men

The relationship between specific insulin binding to insulin receptors on erythrocytes and erythrocyte membrane phospholipid fatty acid pattern was evaluated in 11 healthy men. A significant negative correlation between insulin binding and the proportion of w-6 family essential fatty acids, especially linoleic acid (r = -0.82, p less than 0.01) and arachidonic acid (r = -0.73, p less than 0.05) in erythrocyte membrane was found. On the other hand significant positive correlation between insulin binding and the content of nonessential fatty acids (r = +0.65, p less than 0.05) was seen. Data presented support the hypothesis that the fatty acid composition of membrane phospholipids may modify properties of insulin receptors.

Insulin secretion and insulin action related to the serum phospholipid fatty acid pattern in healthy men

In order to decide whether the phospholipid fatty acid pattern is related to variables determining glucose tolerance, 11 healthy volunteers with normal glucose tolerance were studied. The relationship was evaluated between the proportions of individual fatty acids (FA) in serum phospholipids and (1) insulin secretion, determined by fasting and postglucose plasma insulin levels, and (2) in vivo insulin action, assessed as metabolic clearance rates of glucose during euglycemic clamp studies at two insulin concentrations of approximately 70 microU/mL (MCRglu70) and 500 microU/mL (MCRglu500). It was found that both insulin secretion and insulin action are significantly related to the ratio of omega-6 class essential FA to saturated FA in serum phospholipids. An increase of this ratio is associated with a decrease in total insulin response (r = -0.84, P less than .01), and an increase in MCRglu70 (r = .66, P less than .05) and MCRglu500 (r = .82, P less than .01). The data presented support the hypothesis that phospholipid FA composition might play a role in blood glucose regulation.