The artificial pancreas: two alternative approaches to achieve a fully closed-loop system with optimal glucose control

INTRODUCTION

Diabetes mellitus type 1 is a chronic disease that implies mandatory external insulin delivery. The patients must monitor their blood glucose levels and administer appropriate insulin boluses to keep their blood glucose within the desired range. It requires a lot of time and endeavour, and many patients struggle with suboptimal glucose control despite all their efforts.

MATERIALS AND METHODS

This narrative review combines existing knowledge with new discoveries from animal experiments.

DISCUSSION

In the last decade, artificial pancreas (AP) devices have been developed to improve glucose control and relieve patients of the constant burden of managing their disease. However, a feasible and fully automated AP is yet to be developed. The main challenges preventing the development of a true, subcutaneous (SC) AP system are the slow dynamics of SC glucose sensing and particularly the delay in effect on glucose levels after SC insulin infusions. We have previously published studies on using the intraperitoneal space for an AP; however, we further propose a novel and potentially disruptive way to utilize the vasodilative properties of glucagon in SC AP systems.

CONCLUSION

This narrative review presents two lesser-explored viable solutions for AP systems and discusses the potential for improvement toward a fully automated system: A) using the intraperitoneal approach for more rapid insulin absorption, and B) besides using glucagon to treat and prevent hypoglycemia, also administering micro-boluses of glucagon to increase the local SC blood flow, thereby accelerating SC insulin absorption and SC glucose sensor site dynamics.

Preoperative octreotide therapy and surgery in acromegaly: associations between glucose homeostasis and treatment response

In acromegaly, high GH/IGF-1 levels associate with abnormal glucose metabolism. Somatostatin analogs (SSAs) reduce GH and IGF-1 but inhibit insulin secretion. We studied glucose homeostasis in de novo patients with acromegaly and changes in glucose metabolism after treatment with SSA and surgery. In this post hoc analysis from a randomized controlled trial, 55 de novo patients with acromegaly, not using antidiabetic medication, were included. Before surgery, 26 patients received SSAs for 6 months. HbA1c, fasting glucose, and oral glucose tolerance test were performed at baseline, after SSA pretreatment and at 3 months postoperative. Area under curve of glucose (AUC-G) was calculated. Glucose homeostasis was compared to baseline levels of GH and IGF-1, change after SSA pretreatment, and remission both after SSA pretreatment and 3 months postoperative. In de novo patients, IGF-1/GH levels did not associate with baseline glucose parameters. After SSA pretreatment, changes in GH/IGF-1 correlated positively to change in HbA1c levels (both p < 0.03). HbA1c, fasting glucose, and AUC-G increased significantly during SSA pretreatment in patients not achieving hormonal control (all p < 0.05) but did not change significantly in patients with normalized hormone levels. At 3 months postoperative, HbA1c, fasting glucose, and AUC-G were significantly reduced in both cured and not cured patients (all p < 0.05). To conclude, in de novo patients with acromegaly, disease activity did not correlate with glucose homeostasis. Surgical treatment of acromegaly improved glucose metabolism in both cured and not cured patients, while SSA pretreatment led to deterioration in glucose homeostasis in patients not achieving biochemical control.

The effect of exercise and metformin treatment on circulating free DNA in pregnancy

INTRODUCTION

Some pregnancy complications are characterized by increased levels of cell-free fetal (cffDNA) and maternal DNA (cfmDNA), the latter may also be elevated during physical strain. This study aims at assessing the impact of exercise and metformin intervention in pregnancy, and to compare the levels of cell free DNA in pregnant women with or without PCOS diagnosis.

METHODS

Consecutive women from two previous randomized controlled trials in pregnancy were included. Women came from a trial with organized exercise vs. standard antenatal care in pregnancy and a trial of metformin vs. placebo in PCOS women. Levels of cffDNA, cfmDNA and cell-free total DNA (cftDNA) were measured by qPCR.

RESULTS

Training in pregnancy did not affect the levels of cffDNA, cfmDNA or cftDNA. PCOS-women treated with metformin had lower levels of cfmDNA and cftDNA at week 32 (mean ± SD: 301 ± 162 versus 570 ± 337, p = 0.012, 345 ± 173 versus 635 ± 370, p = 0.019); otherwise the levels were comparable to PCOS-controls. Metformin-treated PCOS-women had higher cffDNA at inclusion, in the 1st trimester; later on in pregnancy the levels in the metformin and placebo groups were equal. A comparison of pregnant women in the exercise study (TRIP) to placebo-treated pregnant PCOS-women, showed the levels of cffDNA, cfmDNA or cftDNA during mid-pregnancy (weeks 18-36) to be equal.

DISCUSSION

Training during pregnancy was not associated with altered levels of cffDNA cfmDNA or cftDNA, but metformin treatment may reduce cfmDNA and cftDNA in pregnant PCOS women.

Preoperative octreotide treatment of acromegaly: long-term results of a randomised controlled trial

OBJECTIVE

Randomised studies have demonstrated a beneficial effect of pre-surgical treatment with somatostatin analogues (SSA) in acromegaly when evaluated early postoperatively. The objective of this study was to evaluate the long-term surgical cure rates.

METHODS

Newly diagnosed patients were randomised to direct surgery (n=30) or 6-month pretreatment with octreotide LAR (n=32). The patients were evaluated 1 and 5 years postoperatively. Cure was defined as normal IGF1 levels and by normal IGF1 level combined with nadir GH <2 mU/l in an oral glucose tolerance test, all without additional post-operative treatment. A meta-analysis using the other published randomised study with long-term analyses on preoperative SSA treatment was performed.

RESULTS

The proportion of patients receiving post-operative acromegaly treatment was equal in the two groups. When using the combined criteria for cure, 10/26 (38%) macroadenomas were cured in the pretreatment group compared with 6/25 (24%) in the direct surgery group 1 year postoperatively (P=0.27), and 9/22 (41%) vs 6/22 (27%) macroadenomas, respectively, 5 years postoperatively (P=0.34). In the meta-analysis, 16/45 (36%) macroadenomas were cured using combined criteria in the pretreatment group vs 8/45 (18%) in the direct surgery group after 6-12 months (P=0.06), and 15/41 (37%) vs 8/42 (19%), respectively, in the long-term (P=0.08).

CONCLUSION

This study does not prove a beneficial effect of SSA pre-surgical treatment, but in the meta-analysis a trend towards significance can be claimed. A potential favourable, clinically relevant response cannot be excluded.

Gestational diabetes mellitus among Norwegian women with polycystic ovary syndrome: prevalence and risk factors according to the WHO and the modified IADPSG criteria

OBJECTIVE

The consequences of the recently proposed International Association of Diabetes in Pregnancy Study Group (IADPSG) criteria for gestational diabetes mellitus (GDM) in women with polycystic ovary syndrome (PCOS) are not known. We compared the prevalence rates and risk factors for GDM in PCOS women according to both the WHO and the modified IADPSG criteria.

DESIGN

Post hoc analyses from a randomized, multicenter study were used.

METHODS

Fasting and 2-h plasma glucose levels were measured using a 75 g oral glucose tolerance test. GDM was diagnosed according to both the WHO and the modified IADPSG criteria.

RESULTS

The prevalence rates of GDM according to the WHO and the modified IADPSG criteria were 9.2 and 15.0% at week 12, 18.7 and 18.7% at week 19, and 25.6 and 24.2% at week 32. Shorter stature and increased insulin levels were correlated with WHO-GDM, but not with modified IADPSG-GDM at weeks 12 and 19. Less weight gain in pregnancy predicted GDM according to both sets of criteria. GDM diagnosis was correlated with less maternal weight loss the first year post-partum.

CONCLUSIONS

No difference was found in the prevalence of GDM between the two sets of criteria used. Less weight gain in pregnancy was associated with GDM, independent of the diagnostic criteria used. Reduced weight loss the first year post-partum in women with GDM raises the question of whether GDM diagnosis per se or the fact that these women lose less weight after pregnancy predicts later diabetes mellitus.

Short-term continuous glucose monitoring: effects on glucose and treatment satisfaction in patients with type 1 diabetes mellitus; a randomized controlled trial

Objective:  To assess whether 4 week's use of a continuous glucose monitoring (CGM) system improves glucose control, treatment satisfaction or health status, as compared to intensified conventional finger-prick measurements (ICFM) in patients with type 1 diabetes mellitus (DM1). Method:  Thirty patients suffering from DM1 for more than three years and treated with either insulin pumps or multiple daily insulin injections, were included in a randomised controlled cross-over trial. They were Caucasians of both genders, between 18 and 50 years, and had moderately well controlled diabetes. The participants performed either ICFM or CGM for 4 weeks, followed by an 8 week's observation period. Thereafter they were crossed over to the opposite intervention. HbA(1c) , hypoglycaemic episodes, treatment satisfaction and health status were assessed at all meetings, although HbA(1c) was the primary endpoint. Results:  At inclusion mean HbA(1c) was 7.8 ± 0.9 %. The mean change in HbA(1c) was -0.2 ± 0.1% and -0.2 ± 0.1% for the CGM and the ICFM periods, accordingly (p = 0.91). The mean changes in HbA(1c) during the combined treatment and observation periods were -0.1 ± 0.1% and -0.2 ± 0.1% for the CGM and the ICFM period, accordingly (p = 0.86). The frequency of severe hypoglycaemic episodes, treatment satisfaction and health status was also equal between the two interventions. No adverse events were observed.

Use of metformin before and during assisted reproductive technology in non-obese young infertile women with polycystic ovary syndrome: a prospective, randomized, double-blind, multi-centre study

BACKGROUND

To study the effect of metformin before and during assisted reproductive technology (ART) on the clinical pregnancy rate (CPR) in non-obese women with polycystic ovary syndrome (PCOS).

METHODS

A multi-centre, prospective, randomized, double-blind study was conducted in eight IVF clinics in four Nordic countries. We enrolled 150 PCOS women with a body mass index <28 kg/m(2), and treated them with 2000 mg/day metformin or identical placebo tablets for ≥ 12 weeks prior to and during long protocol IVF or ICSI and until the day of pregnancy testing. The primary outcome measure was CPR. Secondary outcome measures included spontaneous pregnancy rates during the pretreatment period, and the live birth rate (LBR).

RESULTS

Among IVF treated women (n = 112), biochemical pregnancy rates were identical in both groups (42.9%), and there were no significant differences in the metformin versus the placebo group in CPR [39.3 versus 30.4%; 95% confidence interval (CI): -8.6 to 26.5]. The LBR was 37.5 versus 28.6% (95% CI: -8.4 to 26.3). However, prior to IVF there were 15 (20.3%) spontaneous pregnancies in the metformin group and eight (10.7%) in the placebo group (95% CI: -1.9 to 21.1; P = 0.1047). According to intention to treat analyses (n = 149); significantly higher overall CPR were observed in the metformin versus placebo group (50.0 versus 33.3%; 95% CI: -1.1 to 32.3; P = 0.0391). LBR was also significantly higher with use of metformin versus placebo (48.6 versus 32.0; 95% CI: 1.1 to 32.2; P = 0.0383). No major unexpected safety issues or multiple births were reported. More gastrointestinal side effects occurred in the metformin group (41 versus 12%; 95% CI: 0.15 to 0.42; P < 0.001).

CONCLUSIONS

Metformin treatment for 12 weeks before and during IVF or ICSI in non-obese women with PCOS significantly increases pregnancy and LBRs compared with placebo. However, there was no effect on the outcome of ART per se.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT00159575.

Metformin has no major effects on glucose homeostasis in pregnant women with PCOS: results of a randomized double-blind study

OBJECTIVE

Previous non-randomized and uncontrolled studies indicate major metformin effects on glucose homeostasis in pregnant women with polycystic ovary syndrome (PCOS). We investigated metformin effects on glucose homeostasis in a prospective controlled study.

MATERIAL AND METHODS

Forty pregnant women with PCOS and without known diabetes mellitus were included in the first trimester and randomized to either metformin 850 mg twice daily or placebo. Outcome measures were fasting glucose and insulin at inclusion and changes to pregnancy weeks 19, 32 and 36 and 2 h glucose levels during a 75 g oral glucose tolerance test (OGTT) carried out at inclusion and pregnancy weeks 19 and 32. Insulin resistance (HOMA-IR) and beta-cell function (HOMA-beta) were calculated using the homeostasis assessment model.

RESULTS

At inclusion, 2 h glucose levels during OGTT were higher in the placebo group (7.14 versus 6.03 mmol/L; p = 0.012). Accordingly, 6 out of 22 in the metformin group versus 2 out of 18 women in the placebo group (p = 0.21) had gestational diabetes mellitus at inclusion. At gestational weeks 19 and 32, 2-h plasma glucose levels were equal between the groups. The total proportion of women with gestational diabetes did not differ between the groups, nor did any of the other indices of glucose metabolism and insulin resistance.

CONCLUSIONS

Metformin seems to be without major effects on glucose homeostasis in pregnant women with PCOS.

Metformin treatment in pregnant women with polycystic ovary syndrome--is reduced complication rate mediated by changes in the uteroplacental circulation?

OBJECTIVES

To study a possible effect of metformin on the uteroplacental circulation.

METHODS

Forty pregnant women with polycystic ovary syndrome (PCOS) were enrolled in a randomized, double-blind, placebo-controlled trial of metformin (1700 mg/day) during pregnancy. Doppler ultrasound examinations of the uterine arteries were performed at 12, 19, 24, 32 and 36 gestational weeks and of the umbilical artery at 19, 24, 32 and 36 gestational weeks.

RESULTS

There was a greater mean bilateral uterine artery pulsatility index (PI) at 12 weeks (1.95 vs. 1.58, P = 0.02), and a greater reduction in mean PI from 12 to 19 weeks (P = 0.03) in metformin-treated women. There were no differences in mean PI values between groups at 19, 24, 32 or 36 gestational weeks. Pregnancy complications, such as preterm delivery before 32 weeks, severe pre-eclampsia or serious postpartum events, occurred only in the placebo group (7 of 22 vs. 0 of 18, P = 0.01). There were no associations between uterine artery Doppler measurements and pregnancy complications. We found no differences between groups in mean umbilical artery PI at 19, 24, 32 or 36 gestational weeks.

CONCLUSIONS

In this small randomized trial, metformin treatment in pregnancy reduced uterine artery impedance between 12 and 19 weeks of gestation, and this was associated with reduced complication rate. Published by John Wiley & Sons, Ltd.

Maternal testosterone levels during pregnancy are associated with offspring size at birth

OBJECTIVE

Animal studies have indicated that maternal androgen levels influence the intrauterine environment and development of the offspring. Human data are missing. We therefore investigated the possible association between maternal androgens and offspring size at birth in humans.

DESIGN

A random sample of parous Caucasian women (n=147) was followed prospectively through pregnancy.

METHODS

Maternal serum levels of dehydroepiandrosterone sulfate (DHEAS), androstenedione, testosterone and sex hormone-binding globulin (SHBG) were measured at gestational weeks 17 and 33. The main outcome measures were weight and length at birth. Associations between maternal androgen levels and offspring birth weight and length were investigated using multiple linear regression modeling adjusted for potential confounding by maternal height, pre-pregnancy body mass index, smoking, parity, offspring gender and gestational age at birth.

RESULTS

Elevated maternal testosterone levels at week 17 and 33 were both associated with lower birth weights and lengths. Accordingly, at week 17, an increase in maternal testosterone levels from the 25th to the 75th percentile was associated with a decrease in birth weight by 160 g (95% confidence interval (CI); 29-290 g), while at week 33 that estimate was 115 g (95% CI; 21-207 g). No similar associations were observed for DHEAS, androstenedione or SHBG.

CONCLUSIONS

Elevated maternal testosterone levels during human pregnancy are associated with growth restriction in utero. Our results support animal studies, which have indicated that maternal androgen levels influence intrauterine offspring environment and development.

Metformin reduces pregnancy complications without affecting androgen levels in pregnant polycystic ovary syndrome women: results of a randomized study

BACKGROUND

Investigation of a possible effect of metformin on androgen levels in pregnant women with polycystic ovary syndrome (PCOS).

METHODS

A prospective, randomized, double-blind, placebo-controlled pilot study was conducted. Forty pregnant women with PCOS received diet and lifestyle counselling and were randomized to either metformin 850 mg twice daily or placebo. Primary outcome measures were changes in serum levels of dehydroepiandrosterone sulphate, androstenedione, testosterone, sex hormone-binding globulin, and free testosterone index. Secondary outcome measures were pregnancy complications and outcome. Two-tailed t-tests and chi2-tests were used.

RESULTS

Maternal androgen levels were unaffected by metformin treatment in pregnant women with PCOS. While none of the 18 women in the metformin group experienced a severe pregnancy or post-partum complication, seven of the 22 (32%) women experienced severe complications in the placebo group (P = 0.01).

CONCLUSIONS

Metformin treatment did not reduce maternal androgen levels in pregnant women with PCOS. In the metformin-treated group we observed a reduction of severe, pregnancy and post-partum complications. Metformin treatment of pregnant PCOS women may reduce complications during pregnancy and in the post-partum period.

Metformin treatment before IVF/ICSI in women with polycystic ovary syndrome; a prospective, randomized, double blind study

BACKGROUND

Our aim was to investigate the effect of pre-treatment with metformin in women with polycystic ovary syndrome (PCOS) scheduled for IVF stimulation.

METHODS

Seventy-three oligo/amenorrhoeic women with polycystic ovaries and at least one of the following criteria: hyperandrogenaemia, elevated LH/FSH ratio, hyperinsulinism, decreased SHBG levels or hirsutism, were studied. Normal weight and overweight patients were randomized separately in a prospective, randomized, double blind study. All patients were treated for at least 16 weeks with metformin (1000 mg bid) or placebo ending on the day of HCG injection.

RESULTS

No differences were found in the primary end-points: duration of FSH stimulation 14.4 (13.1-15.7) versus 14.2 (12.6-15.7) days or estradiol on the day of HCG injection 6.8 (5.3-8.2) versus 7.6 (5.6-9.6) nmol/l in the metformin and placebo groups, respectively. The secondary end-points number of oocytes, fertilization rates, embryo quality, pregnancy rates and clinical pregnancy rates were equal. However, in the normal weight subgroup (BMI <28 kg/m(2), n = 27), pregnancy rates following IVF were 0.71 (0.63-0.79) versus 0.23 (0.15-0.31) in the metformin and placebo groups, respectively (P = 0.04). Overall clinical pregnancy rates were equal: 0.51 (0.34-0.68) versus 0.44 (0.27-0.62) in the metformin and placebo groups, respectively. However, in the normal weight subgroup, clinical pregnancy rates were 0.67 (0.43-0.91) and 0.33 (0.06-0.60), respectively (P = 0.06).

CONCLUSIONS

Pre-treatment with metformin prior to conventional IVF/ICSI in women with PCOS does not improve stimulation or clinical outcome. However, among normal weight PCOS women, pre-treatment with metformin tends to improve pregnancy rates. Further studies in subgroups of PCOS women are required.

Six-month treatment with low-dose dexamethasone further reduces androgen levels in PCOS women treated with diet and lifestyle advice, and metformin

BACKGROUND

The purpose of this study was to investigate the effect of low-dose dexamethasone on androgen levels in women with polycystic ovary syndrome (PCOS) treated with diet and lifestyle counselling, and metformin.

METHODS

A prospective, randomized, double blind, placebo-controlled study was carried out. Thirty-eight women with PCOS were randomized to either dexamethasone 0.25 mg daily or placebo for 26 weeks. All received diet and lifestyle counselling at inclusion and metformin 850 mg three times daily during the whole study. Main outcome measures were: androgen levels, body mass index (BMI), insulin c-peptide, fasting glucose and serum lipids. Two-tailed t-tests and Pearson's statistics were used.

RESULTS

Compared with the placebo, dexamethasone reduced testosterone by 27%, androstenedione by 21%, dehydroepiandrosterone sulphate by 46% and free testosterone index by 50% in women with PCOS treated with diet and lifestyle advice, and metformin. BMI, fasting glucose, insulin c-peptide and serum lipid levels were unaffected.

CONCLUSIONS

Six-month, low-dose dexamethasone treatment further reduces androgen levels in metformin-treated PCOS women.

Androgen levels in pregnant women decrease with increasing maternal age

BACKGROUND

To investigate a possible effect of age on maternal androgen levels in uncomplicated pregnancies.

METHODS

A study of 134 parous women with uncomplicated pregnancies was carried out at three university hospitals in Norway and Sweden. Maternal levels of androstenedione, dehydroepiandrosterone sulphate, testosterone and the free testosterone index were measured during weeks 17 and 33 of pregnancy.

RESULTS

Maternal levels of androstenedione and testosterone had a negative association with maternal age in weeks 17 and 33 of pregnancy, while dehydroepiandrosterone sulphate and the free testosterone index were associated negatively in week 33 only. Adjustment for maternal parity, pre-pregnancy body mass index, smoking and fetal gender did not affect the results.

CONCLUSIONS

Maternal androgen levels decrease with increasing maternal age. The cause and possible implication of this finding remain unknown.

[Beta blockers or ACE inhibitors following myocardial infarction in patients with diabetes?]

BACKGROUND

Total mortality after myocardial infarction is about twice as high for diabetic as for non-diabetic subjects. ACE inhibitors are regarded as a first drug for all diabetics, also for post-infarction treatment.

MATERIAL AND METHODS

We have reviewed the literature with an emphasis on the effect on hard end points in diabetic subjects treated for at least six weeks with beta blockers or ACE inhibitors after myocardial infarction.

RESULTS

We identified eight post-infarction studies for which subgroup analyses of diabetic subjects were available, four with beta blockers and four with ACE inhibitors. We found that beta blockers without intrinsic sympathetic activity probably reduce total mortality more than ACE inhibitors do. The reduction of total mortality after treatment with beta blockers was 56-63%, compared to 12-35% after treatment with ACE inhibitors.

INTERPRETATION

Beta blockers should be the preferred choice in post-infarction treatment of diabetics. ACE inhibitors and beta blockers used together give no further reduction in mortality.

Folate administration reduces circulating homocysteine levels in NIDDM patients on long-term metformin treatment

OBJECTIVES

Metformin treatment increases circulating homocysteine levels. We studied whether administration of folate reduces serum total homocysteine levels in patients on long-term metformin treatment.

DESIGN

A prospective, randomized, double-blind, placebo-controlled study lasting for 12 weeks and taking place in a university hospital setting.

SUBJECTS

Thirty patients treated with a metformin dose of at least 1000 mg day-1 for a minimum of 1 year were included. At baseline serum total homocysteine levels were within the reference range. One patient who withdrew and one who died were excluded from the statistical evaluation. Twenty-six of the remaining patients suffered from NIDDM, the other two from hyperlipidaemia.

INTERVENTION

Patients were randomized into two groups at week 0. The folate group received 0.25 mg day-1 of folate in addition to 60 mg day-1 of Fe2+, while the placebo group received only 60 mg day-1 of Fe2+.

MAIN OUTCOME MEASURES

Fasting homocysteine, cysteine, cysteinylglycine, vitamin B12 and folate were measured at week 0, 4 and 12. Changes from week 0 to week 4 and from week 0 to week 12 were calculated.

RESULTS

Folate administration reduced serum levels of total homocysteine in the folate group as compared with the placebo group by 13.9% (P < 0.01) and 21.7% (P < 0.001) at week 4 and 12, respectively. In the folate group versus the placebo group serum levels of vitamin B12 increased by 9.9% (P = 0.010) and 9.6% (P = 0.043) while folate levels increased by 96.9 and 89.9% at week 4 and 12, respectively.

CONCLUSION

The present study indicates that the homocysteine-increasing effect of metformin can be counteracted by folate administration.

Metformin increases circulating tumour necrosis factor-alpha levels in non-obese non-diabetic patients with coronary heart disease

Metformin reduces insulin resistance and hyperinsulinaemia, as well as lipid levels and body weight. The mechanisms behind these effects are likely to involve intracellular insulin signalling. Recent evidence implicates tumour necrosis factor-alpha (TNF-alpha) as a modulatory factor on insulin resistance. The present investigation was undertaken to clarify whether metformin affects TNF-alpha and soluble TNF receptor levels. Sixty non-diabetic men with coronary heart disease were treated with diet and lifestyle advice and lovastatin 40 mg/day during a 4-week run-in period. During this period TNF-alpha and soluble TNF receptor p75 remained unchanged, whereas soluble TNF receptor p55 increased by 8% (P < 0.05). Twelve weeks of metformin treatment increased TNF-alpha by 33% (P < 0.05). This effect was restricted to non-obese patients in whom TNF-alpha increased by 68% (P < 0.01). Soluble TNF receptors p55 and p75 remained unchanged in the whole group, whereas soluble TNF receptor p55 increased by 11% (P < 0.05) in non-obese patients. Since metformin reduces insulin resistance both in obese and non-obese subjects but increases TNF-alpha levels only in the latter, it is concluded that the drug does not exert its effect on insulin resistance through regulation of circulating TNF-alpha levels.

Evidence for dissociation of insulin- and weight-reducing effects of metformin in non-diabetic male patients with coronary heart disease

Metformin effects on insulin resistance and insulin/glucose relationships during an oral glucose tolerance test (OGTT) were investigated in 60 non-diabetic male patients previously treated with coronary artery bypass surgery or angioplasty in an open, 12 week prospective study. During a 4 week run-in period, all patients were treated with diet and lifestyle advice and lovastatin 40 mg daily. Lovastatin treatment was continued in all the patient throughout the study. After randomization, the metformin group got additional treatment with metformin up to 2000 mg/day. Fasting plasma glucose levels and glucose area during OGTT remained unaffected by metformin treatment. Insulin resistance, assessed as the insulin area/glucose area ratio during OGTT decreased by 24% (P = 0.028) in the whole group and by 30% in obese subjects (P = 0.049). Notably, the reduction in body weight by metformin treatment did not correlate with amelioration of insulin resistance or changes in lipid levels. However, changes in insulin resistance correlated with changes in lipid levels. Hence, metformin effects on insulin resistance and body weight appear to be mediated, at least partly, by different mechanisms, while metformin effects on insulin resistance and lipid metabolism are associated in non-diabetic subjects.

Metformin increases total serum homocysteine levels in non-diabetic male patients with coronary heart disease

It is known that the metabolism of homocysteine (Hcy) depends on the vitamins B6, B12 and folate, and furthermore that metformin reduces serum vitamin B12 levels. In order to investigate whether metformin treatment affects serum total Hcy (tHcy) levels we performed an open, prospective, randomised study in 60 non-diabetic male patients with cardiovascular disease. After a 4-week run-in period with lovastatin 40 mg day-1, and diet and lifestyle advice, patients were randomised into two groups, both continuing the run-in treatment. One group received metformin up to 2000 mg day-1, whereas the control group got no additional treatment. After 12 and 40 weeks of metformin treatment, tHcy levels increased moderately but significantly by 7.2% (p < 0.05) and 13.8% (p < 0.05) in the metformin group relative to the control group, whereas serum vitamin B12 levels decreased by 13.4% (p < 0.0005) and 17.7% (p < 0.0005), respectively. Serum folate levels did not change after 12 weeks, but decreased by 8.0% after 40 weeks (p = 0.061) relative to the control group. Serum levels of total cysteine and methylmalonic acid (MMA) did not change. In conclusion, metformin treatment increased tHcy levels and decreased levels of vitamin B12 and folate. Since MMA levels were unchanged, it remains an open question whether the increase in tHcy levels is secondary to reduced vitamin B12 levels, folate levels or a combination of both.

[Sulfonylurea-induced hypoglycemia. An iatrogenic and potentially fatal condition]

Sulfonylureas are the most frequently used peroral antidiabetic drugs in Norway. Five cases of serious sulfonylurea-induced hypoglycemia are described. In one of these cases glibenklamid-induced hypoglycemia was thought to be the direct cause of death. A review of the literature indicates that glibenclamide induces more frequent and serious hypoglycemias than other sulfonylureas do. The author discusses the possible mechanisms behind these differences, and the conditions predisposing to sulfonylurea-induced hypoglycemia. It is recommended to check blood glucose whenever a patient's diagnosis has not been adequately clarified.

Metformin improves blood lipid pattern in nondiabetic patients with coronary heart disease

OBJECTIVES

To study whether the addition of metformin further improves the blood lipid pattern in non-diabetic patients with coronary heart disease already treated with lovastatin, diet and lifestyle advice.

DESIGN

An open, prospective, randomized study in a university hospital setting.

SUBJECTS

Sixty non-diabetic male patients previously treated with coronary artery bypass surgery or angioplasty and with serum cholesterol > or = 6.0 mmol L-1 and/or HDL-cholesterol < or = 1.2 mmol L-1.

INTERVENTIONS

After a 4-week run-in period with lovastatin (40 mg day-1), and diet and lifestyle advice, patients were randomized into two groups, both continuing the run in treatment. One group received metformin up to 2000 mg day-1; the control group got no additional treatment.

MAIN OUTCOME MEASURES

Fasting serum lipids, glucose and weight were registered at entrance (= week-4), and at weeks 0, 4 and 12. Changes from week 0 to week 4 and from week 0 to week 12 were compared. Side-effects of the treatment were also registered.

RESULTS

Metformin lowered the LDL/HDL-cholesterol ratio by 12 and 6% at weeks 4 and 12, respectively, and reduced body weight by 1.8 kg at week 12. There was also a transient lowering effect on LDL-cholesterol and apolipoprotein B. In the normal weight subgroup of patients (body mass index < 27 kg m-2), metformin induced a decrease in total cholesterol (-9%). LDL-cholesterol (-12%). LDL/HDL-cholesterol ratio (-10%) and apolipoprotein B (-7%), as compared to the control group. In this subgroup, body weight and fasting glucose were unaffected by metformin. Thus, the lipid lowering effect in normal weight patients was not secondary to changes in body weight or fasting glucose. In overweight patients (body mass index > 27 kg m-2), metformin had no significant effects on blood lipids, but induced a weight loss of -3.0 kg and a transient reduction of fasting glucose. No side-effects were registered apart from those expected from each individual drug.

CONCLUSIONS

Metformin given for 12 weeks as a supplement to lovastatin, diet and lifestyle advice to non-diabetic male patients with coronary heart disease further improves the lipid pattern in normal weight patients, and reduces weight in the overweight patients. Because metformin is cheap and other lipid lowering drugs are expensive, the potential of metformin as a lipid lowering agent should be further investigated.

[Should insulin treatment be avoided? Blood sugar is not everything in type 2 diabetes]

Cardiovascular disease is frequent and is the main cause of death in type 2-diabetic patients. Hyperinsulinaemia is a risk factor for cardiovascular disease, and insulin accelerates many of the processes leading to atherosclerosis. Studies in type 2-diabetic patients show that high insulin levels correlate with cardiovascular disease and overall mortality. A recent pilot study showed that intensive versus traditional insulin treatment increased the incidence of cardiovascular disease. Therefore treatment regimens that reduce insulin levels should be preferred, at least when equal glucose levels are achieved. In this perspective metformin is the drug of choice. Insulin treatment should be considered only when combined treatment with metformin and sulfonylurea is contraindicated or leads to insufficient blood glucose control. Special caution should be shown with insulin treatment in patients with cardiovascular disease.

[Metformin reevaluated--time for rehabilitation?]

The consumption of metformin in Norway is low. Most probably this is caused by poorly based impressions of small effects and frequent and serious side effects. A review of the literature shows that metformin and sulfonylurea lower average blood glucose values equally well, both in obese and non-obese type 2 diabetic patients. In sulfonylurea failure, addition of metformin lowers the glucose values to the same extent as a shift to insulin monotherapy does. Metformin is anti-hyperglycaemic only, and therefore does not cause hypoglycaemia. The risk of drug-related deaths is no higher with metformin than with sulfonylurea. Metformin improves the lipid profile, and has other effects which could lower risk of cardiovascular complications. The place of metformin in the treatment of type 2 diabetic patients should be reconsidered.