[Glycemic regulation and management of essential hypertension in diabetics with type 2 diabetes mellitus; the 'United Kingdom prospective diabetes study' of diabetic complications]

Patients with type 2 diabetes mellitus often develop micro- and macrovascular complications. In 25% of them, complications are already present at the time of diagnosis. The principal objective of the United Kingdom prospective diabetes study was to determine if good blood glucose control and adequate treatment of hypertension in patients with type 2 diabetes mellitus can prevent development of diabetes-related complications. The question was also studied if they way in which this blood glucose control was achieved and the way of treating the blood pressure affected the prognosis. Blood glucose control was found to reduce the incidence of--especially--microvascular complications. Oral hypoglycaemic agents and insulin both play an important part in achieving good control. Treatment with metformin reduced mortality due to cardiovascular disease in obese patients. Strict control of the blood pressure reduced development of micro- and macrovascular complications; the mortality from diabetes-related disorders and the numbers of patients suffering a stroke or heart failure. Non of the antihypertensive drugs used (an ACE inhibitor and a beta-blocking agent) offered any advantages over the other.

Endothelium-dependent vasodilatation, plasma markers of endothelial function, and adrenergic vasoconstrictor responses in type 1 diabetes under near-normoglycemic conditions

It is unknown whether and to what extent changes in various endothelial functions and adrenergic responsiveness are related to the development of microvascular complications in type 1 diabetes. Therefore, endothelium-dependent and endothelium-independent vasodilatation, endothelium-dependent hemostatic factors, and one and two adrenergic vasoconstrictor responses were determined in type 1 patients with and without microvascular complications. A total of 34 patients with type 1 diabetes were studied under euglycemic conditions on two occasions (11 without microangiopathy, 10 with proliferative and preproliferative retinopathy previously treated by laser coagulation, 13 with microalbuminuria, and 12 healthy volunteers also were studied). Forearm vascular responses to brachial artery infusions of N(G)-monomethyl-L-arginine (L-NMMA), sodium nitroprusside, acetylcholine (ACh), clonidine, and phenylephrine were determined. The ACh infusions were repeated during coinfusion of L-arginine. Furthermore, plasminogen activator inhibitor type 1 (PAI-1) activity, tissue plasminogen activator antigen levels, von Willebrand factor antigen levels, tissue factor pathway inhibitor (TFPI) activity, and endothelin-1 levels were measured. No differences in endothelium-dependent or endothelium-independent vasodilatation or adrenergic constriction were observed between the diabetic patients and the healthy volunteers. In comparison to the first ACh infusion, the maximal response to repeated ACh during L-arginine administration was reduced in the diabetic patients, except in the patients with proliferative and preproliferative retinopathy previously treated by laser coagulation. In these patients, the combined infusion of L-arginine and ACh resulted in an enhanced response. TFPI activity was elevated, and PAI-1 activity was reduced in the type 1 diabetic patients. Furthermore, PAI-1 activity was positively correlated with urinary albumin excretion (r = 0.48, P < 0.01) and inversely correlated with the vasodilatory response to the highest ACh dose (r = -0.37, P < 0.05). The response to the highest ACh and L-NMMA dose were positively correlated with mean arterial blood pressure (r = 0.32, P < 0.01; r = 0.41, P < 0.01, respectively). Forearm endothelium-dependent and endothelium-independent vasodilatation and adrenergic responsiveness were unaltered in type 1 diabetic patients with and without microvascular complications. Relative to healthy control subjects, endothelium-dependent vasodilatation was depressed during a repeated ACh challenge (with L-arginine coinfusion) in the diabetic patients without complications or with microalbuminuria. In contrast, this vasodilatation was enhanced in the patients with retinopathy. Elevation of TFPI was the most consistent marker of endothelial damage of all the endothelial markers measured.

Mechanical properties of mesenteric arteries in diabetic rats: consequences of outward remodeling

Diabetes induces hemodynamic and biochemical changes that can influence mechanical properties of arteries. Structure and mechanics of mesenteric small arteries were investigated in rats with streptozotocin-induced diabetes (duration 7-9 wk). The external diameter of mesenteric artery branches was measured in control (n = 9) and diabetic (n = 7) Wistar Rp rats at baseline and during pressurization in situ (0-150 mmHg) under normal and passive smooth muscle conditions. Mean arterial pressure and mesenteric artery pressure were not significantly different. Baseline mesenteric artery diameter was larger in the diabetes-induced group (439 +/- 12 vs. 388 +/- 18 micrometers, P < 0.05). Media cross-sectional area of arteries from diabetic rats was not significantly increased (0.0149 +/- 0.0015 vs. 0.0122 +/- 0.0007 mm2). Cross-sectional compliance was significantly increased in diabetic rats at intraluminal pressures ranging from 25 to 75 mmHg (P < 0.005), whereas cross-sectional distensibility was not modified. Wall tension and circumferential wall stress were increased in diabetes. These results indicate that mesenteric small arteries of diabetic rats display eutrophic outward remodeling associated with increased wall tension and circumferential wall stress.

Substrate utilization and thermogenic responses to beta-adrenergic stimulation in obese subjects with NIDDM

OBJECTIVE

This study intended to investigate disturbances in beta-adrenergically-mediated substrate utilization and thermogenesis in obese subjects with mild non insulin-dependent diabetes mellitus (NIDDM).

DESIGN

Following a baseline period of 30 min, the beta-agonist isoproterenol (ISO) was administered in increasing doses of 6, 12, and 24 ng/kgFFM x min, each dose for 30 min.

SUBJECTS

Nine healthy lean males (CON, 50.6+/-2.4 y, % body fat: 16.0+/-1.8) and 10 obese subjects with NIDDM (51.8+/-2.4 y, % body fat 34.1+/-1.9).

RESULTS

Basal non esterified fatty acid concentrations (NEFA) and basal fat oxidation (absolute or expressed per unit fat free mass, FFM) were significantly higher in NIDDM as compared to CON, whereas basal carbohydrate (CHO) oxidation was significantly lower. The ISO-induced increase in NEFA-concentrations was blunted in NIDDM (delta at 24 ng/kgFFM x min: CON: 717+/-59 micromol/l vs NIDDM: 358+/-97 micromol/l, P< 0.01). The non-protein respiratory exchange ratio (RER) did not change in NIDDM and significantly decreased in CON during ISO-infusion (P < 0.05), reflecting the tendency towards a blunted increase in fat oxidation in NIDDM (delta fat ox at 24 ng; CON: 0.025+/-0.005 g/min vs NIDDM 0.016+/-0.007 g/min). The ISO-induced thermogenic response was comparable in NIDDM and CON (at 24 ng %increase above baseline: CON: 16.8+/-2.2% vs NIDDM: 14.7+/-0.9%). At all time points, there were no significant differences in circulating ISO and noradrenaline concentrations. Basal adrenaline (A) concentrations and A concentrations during ISO-infusion were significantly lower in NIDDM (basal A; CON: 64+/-15 pg/ml vs NIDDM: 25+/-2 pg/ml, P < 0.001).

CONCLUSION

There appear to be deviations in beta-adrenoceptor mediated fat utilization and adrenal medulla function in obesity-associated NIDDM. The impairments in sympathetically mediated fat utilization have previously been observed in 'simple' obese subjects, indicating that these disturbances are confined to the obese state per se.

A 1-year multicenter randomized double-blind comparison of repaglinide and glyburide for the treatment of type 2 diabetes. Dutch and German Repaglinide Study Group

OBJECTIVE

Repaglinide is a newly developed oral blood glucose-lowering agent that exerts its effect by stimulating insulin secretion. This multicenter study was designed to compare the efficacy and safety of this drug with glyburide in a 1-year randomized double-blind study of outpatients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

A total of 424 subjects (154 women, 270 men) participated and had the following characteristics: age, 61 +/- 9 years; duration of diabetes. 8 years (range 0.5-35); BMI, 28.3 +/- 3.5 kg/m2; HbA1c, 7.1 +/- 1.4%; and fasting plasma glucose, 10.8 +/- 3.1 mmol/l. The majority of the subjects (91%) were previously treated with sulfonylurea, alone or in combination with metformin. The patients were randomized to a 2:1 ratio of repaglinide (0.5-4 mg t.i.d.) or glyburide (1.75-10.5 mg daily) treatment. The study protocol included a screening visit to assess patient eligibility; a titration period of 6-8 weeks, during which the dosages of repaglinide and glyburide were optimized; and a subsequent 12-month treatment period on fixed, optimal dosages.

RESULTS

The trial was completed by 320 subjects, 211 (74%) in the repaglinide and 109 (78%) in the glyburide group. HbA1c initially decreased in both groups and then increased during the second half-year of the maintenance period to a similar extent in the repaglinide and glyburide subjects (0.58 and 0.45% vs. at screening, respectively). In the small group of subjects who previously controlled their condition with diet only (n = 37), a sustained improvement of metabolic control could be observed with both drugs, which was slightly better with glyburide than with repaglinide (theta HbA1c -2.4 vs. -1.0%; P < 0.05). The same trends were seen with fasting plasma glucose. There were no changes in serum lipids. Over the course of the study, 15% of the repaglinide-treated and 13% of glyburide-treated subjects withdrew due to adverse events, mostly hyperglycemia. No differences in adverse events between both drugs were reported. There were no differences in incidences of hypoglycemia.

CONCLUSIONS

Repaglinide is a safe and efficacious oral blood glucose-lowering agent, with a potency similar to that of glyburide. Its rapid onset of action and hepatic clearance allows meal-related administration, including in subjects with impaired kidney function.

Prognostic factors for successful insulin therapy in subjects with type 2 diabetes

OBJECTIVE

To assess which factors influence or predict the efficacy of insulin therapy in subjects with type 2 diabetes, who were poorly controlled despite maximal doses of oral glucose lowering agents.

RESEARCH DESIGN AND METHODS

Seventy-five patients with type 2 diabetes participated (mean age (+/- SD), 67 +/- 8 years; body mass index, 25.8 +/- 5.0 kg/m2; median time since diagnosis of diabetes, 8 years (range 1-36); 27 males and 48 females). They were transferred to insulin therapy, in which case either insulin alone, or a combination of insulin and glibenclamide was employed. The importance of baseline parameters (glycaemic control, beta-cell function, measures of insulin resistance) was assessed by comparing good and poor responders (defined as achieved HbA1c < 8.0 or > 9.0%) to insulin therapy, and by multiple logistic regression analysis of these baseline parameters and achieved metabolic control.

RESULTS

During insulin therapy, HbA1c levels decreased from 10.9 +/- 1.3 to 8.2 +/- 1.1% (p < 0.001), and fasting blood glucose levels decreased from 14.0 +/- 2.3 to 8.2 +/- 2.1 mmol/l (p < 0.001). Thirty patients reached HbA1c levels < 8.0%, 21 of them even < 7.5%. The mean increase in body weight was 4.5 kg. HbA1c after 6 months was 7.0 +/- 0.6% in the good responders, and 9.8 +/- 0.6% in the poor responders (p < 0.001), despite a comparable insulin dose. Baseline metabolic control was similar in both groups. Also, glucagon-stimulated and calculated insulin secretion, as well as parameters of insulin resistance, such as fasting serum insulin levels, free fatty acids, and serum triglycerides, were not different between both groups, and certainly not higher in the poor responders. Also previous metformin use was not different. However, poor responders were more obese than good responders, and had significantly longer known duration of diabetes. Multiple logistic regression confirmed that only duration of diabetes and body mass index were independent predictors of response to insulin therapy.

CONCLUSIONS

We conclude that in elderly patients with type 2 diabetes improvement of glycaemic control can be achieved at the expense of some weight gain. Measurement of residual insulin secretion prior to institution of insulin treatment does not discriminate between good and poor responders to this model of therapy. Especially in obese patients with longer duration of diabetes more attention is needed in order to achieve optimal glycaemic control. Combination of insulin with newer drugs, like thiazolidinediones, may perhaps achieve this.

Cytochrome P450, peroxisome proliferation, and cytoplasmic fatty acid-binding protein content in liver, heart and kidney of the diabetic rat

Diabetes mellitus generally results in an increased systemic fatty acid mobilization which can be associated with an increase in mitochondrial and peroxisomal beta-oxidation of fatty acids in selected tissues. The latter is usually accompanied by a concomitant increase in the tissue content of cytoplasmic fatty acid-binding protein (FABP) which functions in the intracellular translocation of fatty acids. It was previously found that in liver clofibrate-induced proliferation of peroxisomes and increase in FABP expression each are dependent on the induction by cytochrome P4504A1 -mediated (CYP4A1) formation of dicarboxylic acids. We studied whether peroxisome proliferation and an increase of FABP contents in liver, heart and kidney of streptozotocin-induced diabetic rats are also accompanied by an increase of CYP4A1 activity, as this would indicate a possible regulatory role for dicarboxylic acids in peroxisome proliferation and FABP induction in diabetic organs other than liver. In livers of the diabetic rat, a concomitant increase was observed of the activities of CYP4A1 and the peroxisomal key enzyme fatty acyl-CoA oxidase (FACO) and of the FABP content. In the diabetic heart FACO activity and FABP content also increased, but there was no induction of CYP4A1 activity. Conversely, in diabetic kidney there was no increase in FACO activity nor FABP content in spite of a marked induction of CYP4A1 activity. It is concluded that streptozotocin-induced diabetes leads to increased peroxisome proliferation and increased levels of FABP in both liver and heart, which only in liver is accompanied by an induction of the cytochrome P450 system. Consequently, it is not likely that dicarboxylic acids are involved in the induction of peroxisome proliferation in the heart.

Effects of acarbose (Glucobay) in persons with type 1 diabetes: a multicentre study

The aim of this multicentre study was to investigate the effect--in everyday life--of long term administration of acarbose on parameters of glycaemic control, daily insulin requirements, lipid parameters and tolerability in ambulant type 1 diabetic subjects insufficiently controlled with diet and insulin. Furthermore, effects on lipid parameters were to be studied. A total of 16 patients withdrew from the study, 13 of these during the acarbose medication period. For four of these 13 patients the adverse event started during the placebo run-in period. The data of 62 patients (35 men and 27 women, mean age 38 (range 18-64) years, median duration of diabetes 10 (range 1-40) years) were valid for statistical analysis. The median daily dose of acarbose at the final assessment (i.e. after 16 weeks of active treatment) was 200 (range 75-300) mg. During the placebo run-in period HbA1c levels tended to decrease from 8.9 +/- 1.1 to 8.5 +/- 0.9%. After 8 and 16 weeks of acarbose treatment the mean level had decreased further to 8.1 +/- 0.9 and 8.2 +/- 0.9%, respectively (both P < 0.001). After stopping acarbose HbA1c levels increased again to a mean level of 8.6 +/- 0.9%. Mean levels of HbA1c per centre followed the same profile. Seven-point blood glucose profiles followed the same pattern. None of these changes over time reached statistical significance except for a significant drop during acarbose treatment of the time-point 90 min after lunch (P < 0.01). After stopping acarbose treatment values returned to pre-study levels. For total cholesterol, HDL-cholesterol, triglycerides, Apo A1 and Apo B, and Lp(a) no significant changes were observed. Daily insulin dose was 48 (range 26-92) U at the start of the study and did not change. The most frequent reported adverse events were flatulence (43%), diarrhoea (27%), and abdominal pain (11%). We conclude that acarbose up to 3 x 100 mg/day can be a valuable adjunct to insulin in improving metabolic control in persons with type 1 diabetes.

Lipid peroxidation in type 2 diabetes: relationship with macrovascular disease?

BACKGROUND

Macrovascular disease is the leading cause of death in diabetes. The increased risk of atherosclerosis in diabetes may be partly explained by increased lipid peroxidation.

METHODS

We assessed lipid peroxidation in subjects with type 2 diabetes with (n = 23) and without (n = 23) macrovascular complications versus healthy age-matched controls (n = 13). The diabetic groups were matched for glycemic control (mean HbA1c = 9%), and for age had similar known duration of diabetes.

RESULTS

Plasma TBARS were comparable between diabetic subjects with and without macrovascular complications (1.89 +/- 0.32 and 1.81 +/- 0.28 mumol/l) and elevated compared to healthy controls (1.64 +/- 0.26 mumol/l, p = 0.025). Ratios of IgG and IgM antibodies to oxidized vs. native LDL were comparable between diabetic subjects and controls, and also between diabetic subjects with or without macrovascular complications. The lag phase, an index of the resistance of LDL to oxidation, was significantly longer in diabetic patients with macrovascular complications (66 +/- 8 min) vs. those without macrovascular complications and controls (resp. 59 +/- 7 and 56 +/- 7 min, p < 0.05). An explanation may be the frequent use of drugs with possible antioxidant potential, e.g. beta-blocking agents, ACE-inhibitors and calcium entry blockers by these patients. Surprisingly, plasma vitamin E levels were higher in diabetic subjects.

CONCLUSIONS

We found no evidence of increased lipid peroxidation in diabetic subjects with macrovascular complications, but an increased resistance to oxidation in this group, probably due to an altered antioxidant status. The increased TBARS level in diabetic subjects contrasts with the other indices of lipid peroxidation and may be related to prevalent hyperglycemia and should therefore be interpreted cautiously.

Consequences of long-term hyperparathyroidism

We describe a young woman with long-term untreated hyperparathyroidism with a superimposed vitamin D deficiency and an extremely decreased bone mineral density that was complicated by a vertebral fracture. Despite pretreatment with intravenous pamidronate and short-term vitamin D supplementation, severe and long-standing hypocalcaemia ('hungry bone syndrome') developed after parathyroidectomy. We discuss the consequences of hyperparathyroidism, especially the effects on bone, the complications of parathyroidectomy and the possibilities of preoperative treatment with bisphosphonates.

Arteriolar reactivity in conscious diabetic rats: influence of aminoguanidine treatment

The effect of 6 weeks' streptozotocin (STZ)-induced (70 mg/kg) diabetes and aminoguanidine (AG) treatment (50 mg/kg s.c. or 250-750 mg/l given in drinking water) on arteriolar reactivity to vasoactive substances was investigated in conscious rats. Studies were performed in untreated control rats (n = 13), STZ-induced diabetic rats (n = 11), AG-treated control rats (n = 12), and AG-treated diabetic rats (n = 12). Rats were provided with a dorsal microcirculatory chamber that allowed intravital microscopy of striated muscle arterioles of varying diameter (A1, large; A2, intermediate; and A3, small arterioles) in conscious animals. The mean arterial pressure (MAP) and arteriolar diameter responses to intravenous infusion of the following drugs were examined: the endothelium-dependent vasodilator acetylcholine (ACh; 3, 10, and 30 microg x kg(-1) x min(-1)), the potassium-channel opener levcromakalim (LC; 30 microg/kg), and the vasoconstrictor agents ANG II (0.1 and 0.3 microg x kg(-1) x min(-1)) and norepinephrine (NE; 0.2, 0.6, and 2.0 microg x kg(-1) x min(-1)). Baseline MAP was lower in both diabetic groups versus the nondiabetic groups (P < 0.05). AG treatment had no influence on baseline MAP. The absolute change in MAP after drug infusion tended to be lower in the diabetic rats than in their nondiabetic littermates. Arteriolar vasodilatory responses to ACh and LC were attenuated in the diabetic animals (1 +/- 7 vs. 19 +/- 7% [P < 0.05] and 7 +/- 3 vs. 34 +/- 8% [P < 0.01] in A2, respectively). AG treatment of diabetic animals did not prevent the development of this disturbance. Vasoconstrictor responses were not influenced by the diabetic state. In the intermediate arterioles of AG-treated control rats, a hyperresponse was observed after ANG II infusion (-10 +/- 2 vs. -2 +/- 2%; P < 0.05) and a hyporesponse was observed after ACh and LC infusion (2 +/- 3 and 15 +/- 6%, respectively; P < 0.05 vs. untreated control rats). These data indicate that 6 weeks of experimental diabetes is associated with a decreased endothelium-dependent and -independent vasodilatation. AG treatment had no beneficial effect on this disturbance.

Breakers of advanced glycation end products restore large artery properties in experimental diabetes

Glucose and other reducing sugars react with proteins by a nonenzymatic, posttranslational modification process called nonenzymatic glycation. The formation of advanced glycation end products (AGEs) on connective tissue and matrix components accounts largely for the increase in collagen crosslinking that accompanies normal aging and which occurs at an accelerated rate in diabetes, leading to an increase in arterial stiffness. A new class of AGE crosslink "breakers" reacts with and cleaves these covalent, AGE-derived protein crosslinks. Treatment of rats with streptozotocin-induced diabetes with the AGE-breaker ALT-711 for 1-3 weeks reversed the diabetes-induced increase of large artery stiffness as measured by systemic arterial compliance, aortic impedance, and carotid artery compliance and distensibility. These findings will have considerable implications for the treatment of patients with diabetes-related complications and aging.

Efficacy and safety of a new cholesterol synthesis inhibitor, atorvastatin, in comparison with simvastatin and pravastatin, in subjects with hypercholesterolemia

BACKGROUND

High levels of total and LDL-cholesterol are associated with an increased risk of atherosclerotic vascular disease. Lowering of serum cholesterol levels by pharmacologic intervention with inhibitors of cholesterol synthesis, the so-called statins, reduces the incidence of cardiovascular events in subjects with and without atherosclerotic manifestations. In a 16-week, multicenter, randomized, open-label cross-over study we compared the efficacy and safety of the new compound atorvastatin for reducing LDL-cholesterol with simvastatin or pravastatin.

METHODS

Following a 4-week placebo-controlled baseline period patients with LDL-cholesterol between 4.1 and 6.2 mmol/l and serum triglycerides below 3.4 mmol/l were randomly assigned to treatment either with 5 or 20 mg atorvastatin, or with 10 mg simvastatin or 20 mg pravastatin once daily for 4 weeks. After a placebo-washout period of 4-6 weeks, patients switched to the alternate treatment. At the end of weeks 3 and 4 of each study phase the serum concentrations of lipid parameters and apolipoproteins as well as safety parameters were determined.

RESULTS

A total of 78 subjects entered the study. Treatment with 5 mg atorvastatin reduced total and LDL-cholesterol by 21 and 27%, respectively, which was similar to 10 mg simvastatin (total cholesterol -20%, LDL-cholesterol -28%) and 20 mg pravastatin (-18 and -24%, respectively). The effects of this low dose of atorvastatin on triglyceride levels (-16%) was not different from that of simvastatin and pravastatin (-8 and -11%, respectively). Treatment with 20 mg atorvastatin caused significantly larger reductions in total cholesterol (-33%) and LDL-cholesterol (-44%), serum triglycerides (-23%), and apo B (-40%) compared to simvastatin and pravastatin. Atorvastatin was well-tolerated, and no serious or medically important adverse events were observed.

CONCLUSIONS

We conclude that atorvastatin is a safe and very efficacious cholesterol-lowering agent, which also possesses significant triglyceride-lowering properties.

Beneficial gamma-knife radiosurgery in a patient with Nelson's syndrome

A 50-year-old female patient with Cushing's disease had undergone transsphenoidal removal of the pituitary adenoma and conventional radiotherapy in 1988. Since no remission was achieved, she underwent bilateral adrenalectomy in May 1989. During out-patient follow-up, she developed signs and symptoms due to invasive Adrenocorticotrophic hormone (ACTH)-producing macroadenoma (Nelson's syndrome) in 1994. ACTH levels at that time were 3400 ng/l. Near-total surgical resection of a 2.0 x 2.5 pituitary tumour which slightly extended laterally into the cavernous sinus was achieved by subfrontal approach in June 1994. However, she rapidly developed a recurrence of her complaints, with a visual field defect inferior-nasal of the left eye, and a second operation was carried out in November 1994. Culture of the tumour's cells revealed significant inhibition of ACTH production by bromocriptine. Adjuvant treatment with this drug therefore was started in November 1994. Because of the rapid recurrence it was decided to treat her with gamma-knife radiosurgery. The dose that was given in January 1995 was 12 Gy to the border and 40 Gy into the centre of the tumour. During a follow-up of more than 2 years, no recurrence, but even a minor reduction of tumour mass was observed by magnetic resonance imaging (MRI). Plasma ACTH levels decreased gradually to levels between 200 and 400 ng/l, and ophthalmologic complaints disappeared. It is concluded that gamma-knife radiosurgery may be a good alternative for patients with Nelson's syndrome who have rapidly recurring disease.

[Short-acting insulin analogs]

Patients with diabetes mellitus type I usually are treated with a multiple injection regimen comprising rapid-acting insulin before meals and intermediate-acting insulin at bedtime. Recently, the rapid-acting insulin analogue insulin LISPRO was introduced on the Dutch market. This form of insulin is very rapidly taken up into the bloodstream from the subcutaneous tissue. The advantages of the use of insulin LISPRO are the comfort of injecting the insulin just before a meal, the more rapid correction of incidental hyperglycaemia and the slightly lower incidence of (nocturnal) hypoglycaemia in comparison with conventional rapid-acting insulin. There is no argument in favour of switching diabetics to insulin LISPRO if they are well-controlled with normal rapid-acting insulin and have few episodes of hypoglycaemia. In some persons the duration of action of insulin LISPRO may be too short, leading to preprandial hyperglycaemia. This can be avoided by using a second injection of intermediate-acting insulin, either before breakfast or before lunch.

Shock of unknown origin--think of mastocytosis!

Shock of unknown origin may be due to mastocytosis, in which excessive release of mast cell mediators can cause severe systemic vasodilation. We describe a patient who experienced two life-threatening episodes of shock which appeared to be due to mastocytosis. Therapeutic options are discussed.

Peripheral blood flow and noradrenaline responsiveness: the effect of physiological hyperinsulinemia

OBJECTIVE

Insulin seems to have vasodilator properties, but it is unclear if insulin in postprandial concentrations is a specific vasodilator of skeletal muscle resistance arterioles only or that various types of vessels are affected. The aim of the present study was to determine the direct effects and the time course of regional/local physiological hyperinsulinemia on skeletal muscle arterioles, skin blood flow and peripheral venous tone and the responsiveness of these different vascular beds to noradrenaline.

METHODS

In protocol I (n = 12) we infused insulin into the brachial artery for 180 min (3.5 mU/min) and evaluated the effects on forearm (muscle) blood flow (FBF) and skin blood flow (SBF). Furthermore, noradrenaline (0.025, 0.01 and 0.4 microgram/min) was infused (i.a.) at baseline, at 90 and 180 min after the start of insulin. In protocol 2 (n = 10) the same regional forearm hyperinsulinemia was achieved, but now the local venous responsiveness to noradrenaline (1.7-55 ng/min, at baseline and at 90 and 180 min) was measured in a dorsal hand vein. In protocol 3 we evaluated the local effects of different doses of insulin (1-100 mU/min) infused directly into hand veins preconstricted with phenylephrine.

RESULTS

Forearm hyperinsulinemia (approximately 50 mU/l) led to a significant increase in FBF after 180 min (median 26%, interq ranges 5-50, P < 0.05), while SBF was not altered. Forearm hyperinsulinemia did not affect the noradrenergic responsiveness in skeletal muscle or skin. Infused locally into hand veins only the highest dose of insulin (100 mU/min) caused a minor venodilation (7% [2.4-12.5], P < 0.05).

CONCLUSION

Regional forearm physiological hyperinsulinemia has a vasodilator effect on resistance vessels in skeletal muscle, but is slow in onset (180 min). However, skin vasculature and peripheral veins are not affected by this hyperinsulinemia.

Increased tissue factor pathway inhibitor (TFPI) and coagulation in patients with insulin-dependent diabetes mellitus

Recently, we found an increase in tissue factor pathway inhibitor (TFPI) activity in patients with insulin-dependent diabetes mellitus (IDDM). This increase in TFPI activity could be the result of increased thrombin formation and/or altered binding of TFPI to glycosaminoglycans. We studied TFPI activity (chromogenic assay) in relation to prothrombin F1 + 2 fragments and endogenous thrombin potential (ETP), in 46 IDDM patients, and 18 age and sex-matched healthy controls. Prothrombin, antithrombin and thrombomodulin were also determined. In IDDM patients, TFPI activity and F1 + 2 levels were significantly higher, while ETP, prothrombin antigen levels, and antithrombin activity were lower as compared to the controls. In IDDM patients with microalbuminuria, a manifestation of generalized angiopathy, TFPI activity, F1 + 2 and thrombomodulin levels were higher than in patients with only retinopathy or patients without complications. No correlation between TFPI activity, F1 + 2 levels and thrombomodulin was found, while TFPI activity was negatively correlated with ETP (r = -0.27). Microalbuminuria was significantly correlated with TFPI activity (r = 0.46), F1 + 2 (r = 0.56), and thrombomodulin (r = 0.52). In TFPI-depleted plasma, ETP increased, indicating that ETP is affected by TFPI. In conclusion, the increase in TFPI activity in IDDM patients may not be considered to be a reaction on a procoagulant state. It is hypothesized that vascular damage, leading to alterations in glycosaminoglycans, is in part responsible for the changes in TFPI activity, F1 + 2 levels and ETP.

Comparison of different insulin regimens in elderly patients with NIDDM

OBJECTIVE

To compare the metabolic effects of three different frequently used regimens of insulin administration on blood glucose control and serum lipids, and the costs associated with this treatment, in subjects with NIDDM, who were poorly controlled with oral antihyperglycemic agents.

RESEARCH DESIGN AND METHODS

We studied 95 elderly patients with NIDDM (age 68 +/- 9 years, BMI 26.0 +/- 4.6 kg/m2, and median time since diagnosis of diabetes 9 years [range 1-37]; 37 men, 58 women), who were poorly controlled, despite diet and maximal doses of oral antihyperglycemic agents. Three insulin administration regimens were compared during a 6-month period: patients were randomized for treatment with a two-injection scheme (regimen A) or a combination of glibenclamide with one injection of NPH insulin, administered either at bedtime (regimen B) or before breakfast (regimen C), and insulin treatment was mainly instituted in an outpatient setting.

RESULTS

After 6 months of insulin treatment, fasting blood glucose of the total patient population had decreased from an average of 14.1 +/- 2.2 to 8.3 +/- 2.0 mmol/L (P < 0.001), and HbA1c fell from 11.0 +/- 1.3 to 8.3 +/- 1.2% (P < 0.001); 34 patients reached HbA1c levels below 8.0%, 25 of them even below 7.5%. With two insulin injections daily, HbA1c decreased from 11.2 +/- 1.3 to 8.2 +/- 1.2%, while during combined treatment, HbA1c fell from 10.5 +/- 1.2 to 8.1 +/- 1.1% (regimen B) and from 11.1 +/- 1.3 to 8.5 +/- 1.1% (regimen C). Comparable improvement of the other measures of glycemic control, lipids and lipoproteins, was observed in the different treatment regimens. Body weight increase was moderate (mean +/- 4.0 kg) and similar in all patient groups. One-third of patients starting with one insulin injection daily needed a second injection to control glycemia. One episode of severe hypoglycemia was observed. Combined insulin-sulfonylurea treatment was almost 20% more expensive than twice-daily administration of insulin alone.

CONCLUSIONS

Insulin treatment can safely be instituted in elderly patients with NIDDM. However, it is difficult to obtain optimal glycemic control. Insulin has moderate beneficial effects on serum lipoproteins. Although on the basis of glycemic control and weight gain, no preference for any treatment regimen can be discerned, twice-daily insulin administration is the most simple and cost-effective regimen.

New treatments for patients with type 2 diabetes mellitus

In subjects with type 2 diabetes, both defects of insulin secretion and insulin resistance contribute to the development of hyperglycaemia. The major goals of treatment are to optimise blood glucose control, and normalise the associated lipid disturbances and elevated blood pressure. Pharmacologic treatment is often necessary. This paper discusses new forms of oral treatment for subjects with type 2 diabetes. These include a new sulphonylurea compound glimepiride (Amaryl), which binds to a different protein of the putative sulphonylurea receptor than glibenclamide, and seems to have a lower risk of hypoglycaemia. A new class of drugs with insulin secretory capacity, of which repaglinide (NovoNorm) is the leading compound, is now in phase III clinical trials. Alpha-glucosidase inhibitors reversibly inhibit alpha-glucosidase enzymes in the small intestine, which delays cleavage of oligo- and disaccharides to monosaccharides. This leads to a delayed and reduced blood glucose rise after a meal. Two compounds are in development or have been marketed, ie, miglitol and acarbose (Glucobay). Another new class of drugs is the thiazolidine-diones, which seem to work by enhancing insulin action. The 'insulin sensitising' effects of the leading compounds, troglitazone and BRL 49653C, do not involve any effect on insulin secretion. These drugs also seem to beneficially influence serum cholesterol and triglyceride levels. Oral antihyperglycaemic agents can be used only during a limited period of time in most patients, after which the diabetic state 'worsens' and insulin therapy has to be started. In this light, two new forms of treatment which require subcutaneous injections are also discussed: the synthetic human amylin analogue AC137 (pramlintide) and glucagon-like peptide-1 (7-36)-amide, a strong glucose-dependent stimulator of insulin secretion. It remains to be seen whether these compounds can be developed further for clinical use in patients with diabetes.

Miglitol (Bay m 1099) has no extraintestinal effects on glucose control in healthy volunteers

In this double-blind, cross-over, placebo-controlled, randomized study, possible extraintestinal effects of miglitol, an absorbable alpha-glucosidase inhibitor, were investigated. Sixteen healthy male volunteers underwent two 75 g oral glucose tolerance tests with concomitant administration of miglitol or placebo. Peak and post-peak areas under the curve values for blood glucose, serum insulin and serum C-peptide after miglitol were not different from those found after placebo. The post-peak AUC-ratio (AUC (peak, 180 min) on miglitol/AUC (peak, 180 min) on placebo) was for glucose 1.15 (CI 0.94-1.40, P = 0.16), for insulin 1.12 (CI 0.95-1.33, P = 0.17) and for C-peptide 0.98 (CI 0.81-1.18, P = 0.82). It is concluded that miglitol exerts no clinically relevant extraintestinal effects on glucose control.

Long-term assessment of glucose control by haemoglobin-AGE measurement

BACKGROUND

Control of blood glucose is important in reducing both the incidence and the severity of complications in diabetes mellitus. One consequence of long- term hyperglycaemia is the formation and accumulation of advanced glycation end-products (AGEs) on tissue macromolecules. An AGE-modified form of human haemoglobin (Hb-AGE) present at high levels in the red cells of diabetic patients, differs from glucose-derived Amadori product HbA1c in being chemically irreversible and thus persisting for the circulating life of the red cell. We therefore compared Hb- AGE with HbA1c as indicators of long-term blood glucose control.

METHODS

In an open study we measured circulating HbA1c and Hb-AGE concentrations in eight patients with poorly controlled non-insulin-dependent diabetes after a switch to subcutaneous insulin therapy and careful blood glucose monitoring.

RESULTS

After 16 weeks of insulin therapy, the mean HbA1c had decreased from 13.3 (SD 1.2) to 7.3 (0.9)% and the mean Hb-AGE from 12.1 (1.5) to 7.3 (1.3) U/mg Hb. The rate of Hb-AGE decline was 23% slower than that of HbA1c (p=0.044).

INTERPRETATION

The observation that Hb-AGE declines more slowly than HbA1c is consistent with the irreversible nature of the AGE product. Because of this property, Hb-AGE may prove superior to HbA1c as a long-term index of circulating glucose concentrations.