Low density lipoprotein-cholesterol variability in patients with type 2 diabetes taking atorvastatin compared to simvastatin: justification for direct measurement?

AIM

The benefit of direct, as opposed to calculated, low density lipoprotein -cholesterol (LDL-C) measurement remains unclear. This study compared the biological variability of direct LDL in patients with type 2 diabetes (T2DM) on equivalent doses of the short half-life statin, simvastatin or the longer half-life statin, atorvastatin.

METHODS

A cross-over study of biological variation of lipids in 26 patients with T2DM taking either simvastatin 40 mg (n = 10) or atorvastatin 10 mg. After 3 months on one statin, fasting lipids were measured on 10 occasions over a 5-week period. The same procedure was then followed on the other statin. The variability of LDL-C was established using a Beckman direct assay.

RESULTS

As a group, mean LDL was no different between statins (mean +/- s.d.) (1.69 +/- 0.60 mmol/l simvastatin vs. 1.67 +/- 0.60 mmol/l atorvastatin, p = 0.19). However, in all patients, the intraindividual biological variability of LDL while taking simvastatin was markedly higher than with atorvastatin (average s.d. = 0.17 mmol /l simvastatin vs. 0.01 mmol/l, p < 0.0001). Friedewald calculated LDL variability was no different between statins (average s.d. = 0.34 mmol /l simvastatin vs. 0.21 mmol/l atorvastatin, p = 0.19).

CONCLUSIONS

In contrast to calculated values, direct measurement revealed LDL to be much more stable (the s.d. being an order of magnitude) in T2DM patients taking atorvastatin rather than simvastatin. This means LDL targets can be consistently met with less lipid monitoring using atorvastatin rather than simvastatin. Direct LDL measurement may therefore have a particular role in monitoring patients on statin treatment.

Atorvastatin-related thrombocytopenic purpura

A 44-year-old male patient with a single vessel ischaemic heart disease was referred to the lipid clinic for management of hypercholesterolaemia after an episode of admission with thrombocytopenic purpura secondary to atorvastatin. Atorvastatin was discontinued and his platelet counts improved gradually with steroids. He is now established on a different statin with no further episodes of thrombocytopenia. Though a drug challenge was never done, an idiosyncratic reaction to the initial statin seems to be the most likely cause.

National UK audit of the Short Synacthen® Test

We present the first national audit of the Short Synacthen Test (SST), identifying the clinical, analytical and interpretative procedures adopted by 89 laboratories.

Background

The SST has replaced the insulin stress test as the first-line test to assess adrenal insufficiency and has received considerable attention regarding its sensitivity and specificity. Concerns regarding this test include the bias of cortisol methods, cut-off values used, contraindications and the limitations of the test in diagnosing recent, mild secondary adrenal insufficiency. The audit took into consideration the protocols used by laboratories, the advice provided prior and after the SST and the analytical bias of the methods used.

Methods

A web-based questionnaire using Microsoft FrontPageTM was prepared to collect data from laboratories and provided drop-down lists and other form-field elements to capture additional comments. The resultant data were exported to Microsoft ExcelTM for data clean-up and analysis.

Results

The workloads were highly variable; however, most laboratories were in general agreement to the indications, contraindications, timing and reference ranges. In contrast, there was variability in the bias of the cortisol methods, which had not been translated to the cut-off values used by the majority of laboratories.

Conclusions

The audit has shown that though the preanalytical procedures were similar in most laboratories, there is a requirement to recognize the effect that method bias may have on the reference ranges and consequently on the diagnosis of adrenal insufficiency. There is a need to develop consensus guidelines, which can aid both clinicians and laboratories.

Intensive glucose therapy and clinical implications of recent data: a consensus statement from the Global Task Force on Glycaemic Control

BACKGROUND

There is compelling evidence showing that achieving good glycaemic control reduces the risk of microvascular complications in people with type 1 and type 2 diabetes. Likewise, there is clear evidence to show that achieving good glycaemic control reduces the risk of macrovascular complications in type 1 diabetes. The UKPDS 10-year follow up suggests that good glycaemic control also reduces the risk of macrovascular complications in type 2 diabetes. Despite this, recent results from ACCORD, ADVANCE and VADT present conflicting results and data from the ACCORD trial appear to suggest that very low HbA(1c) targets (<6.0%) may, in fact, be dangerous in certain patient populations.

AIM

To review recent results from ACCORD, ADVANCE and VADT and provide clear guidance on the clinical significance of the new data and their implications for the practising physician treating patients with type 2 diabetes.

METHODS

A Pubmed search was used to identify major randomised clinical trials examining the association between glycaemic control and diabetes-associated complications. The data was reviewed and discussed by the GTF through a consensus meeting. The recommendations for clinical practice in this statement are the conclusions of these analyses and discussions.

RESULTS

Evidence from ACCORD, ADVANCE, VADT and UKPDS suggests that certain patient populations, such as those with moderate diabetes duration and/or no pre-existing CVD, may benefit from intensive blood glucose control. These trials highlight the benefit of a multifactorial treatment approach to diabetes. However, ACCORD results indicate that aggressive HbA(1c) targets (<6.0%) may not be beneficial in patients with existing CVD and a longer duration of diabetes.

CONCLUSIONS

Glycaemic control remains a very important component of treatment for type 2 diabetes and contrasting results from the ACCORD, ADVANCE and VADT should not discourage physicians from controlling blood glucose levels.

The Diabetes Control and Complications Trial: the gift that keeps giving

The Diabetes Control and Complications Trial (DCCT) recruited its first patients in 1983. In 1993, the investigators reported that intensive glycemic treatment of patients with type 1 diabetes mellitus was superior to conventional therapy in preventing the development of microvascular and neurological complications and thus provided definitive proof of the relationship between hyperglycemia and the subsequent risk of diabetic retinopathy, nephropathy and neuropathy. The value of this study, however, did not end there. After the original trial, most participants of the DCCT continued to be followed up in the Epidemiology of Diabetes Interventions and Complications (EDIC) study, which demonstrated the long-term benefits of close glycemic control and provided observational data of a large epidemiological cohort of patients with type 1 diabetes mellitus. Stored samples from the DCCT have also provided an invaluable resource for the identification of new markers of the disease. Recently, the complete dataset of the DCCT and of the initial years of the EDIC have been made publicly available, which allowed independent investigators to help answer their own questions about diabetes. In conclusion, the DCCT continues to provide new insights into type 1 diabetes mellitus, which are of benefit to patients over a quarter of a century after the trial was started.

Effect of glucose variability on the long-term risk of microvascular complications in type 1 diabetes

OBJECTIVE

This study analyzed data from the Epidemiology of Diabetes Interventions and Complications (EDIC) study to see whether longer-term follow-up of Diabetes Control and Complications Trial (DCCT) patients reveals a role for glycemic instability in the development of microvascular complications.

RESEARCH DESIGN AND METHODS

The mean area under the curve glucose and the within-day glucose variability (SD and mean amplitude of glycemic excursions [MAGE]) during the DCCT were assessed to see whether they contributed to the risk of retinopathy and nephropathy by year 4 of the EDIC.

RESULTS

Logistic regression analysis showed that mean glucose during the DCCT and mean A1C during EDIC were independently predictive of retinopathy (each P < 0.001) as well as A1C during EDIC of nephropathy (P = 0.001) development by EDIC year 4. Glucose variability did not add to this (all P > 0.25 using SD or MAGE).

CONCLUSIONS

Glucose variability in the DCCT did not predict the development of retinopathy or nephropathy by EDIC year 4.

Arguments for and against the role of glucose variability in the development of diabetes complications

There is now unequivocal evidence that improving glycemic control in both type 1 and type 2 diabetes reduces the likelihood of developing the micro- and macrovascular complications of the disease. However, it is still unclear whether a patient with very variable glucose is at any different a risk of these problems than someone who has the same mean glucose but much more stable glycemia. This article reviews the evidence that exists to both support and refute the claim that increased glucose variability should be regarded as an independent risk factor for the development of diabetic vascular disease.

The mean and the biological variation of insulin resistance does not differ between polycystic ovary syndrome and type 2 diabetes

Background

There is an assumption that the mean and biological variation of insulin resistance (IR) is less in polycystic ovary syndrome (PCOS), and intuitively higher in type 2 diabetes (T2DM). To test this hypothesis we compared the mean and biological variation in IR in PCOS to that of T2DM and to age- and weight-matched controls.

Methods

Twelve PCOS, 11 matched healthy women; 12 postmenopausal diet-controlled T2DM and 11 matched healthy postmenopausal women were recruited. Blood samples were collected at 4-d intervals on 10 consecutive occasions. The biological variability of IR was derived on duplicate samples.

Results

Mean and biological variability of HOMA-IR for PCOS did not differ from T2DM. Both measures were higher than the matched controls. There was no difference in insulin or IR measures between the body mass index matched pre- and postmenopausal women. Percentage β cell function were 208.8%, 62.3%, 106.5% and 111.9%, respectively, in PCOS, postmenopausal women with T2DM, healthy premenopausal and healthy postmenopausal women.

Conclusions

The progression from PCOS to the development of T2DM is unlikely to be due to a further increase in IR (or variability), but rather the progressive failure of pancreatic beta cells with a decrease in insulin production. The clinical trial registration number for this study is ISRCTN65353256.

Effect of metformin, orlistat and pioglitazone treatment on mean insulin resistance and its biological variability in polycystic ovary syndrome

CONTEXT

Mean insulin resistance (IR) is greater and it is also more variable in overweight women with polycystic ovarian syndrome (PCOS) compared to weight matched controls. Whilst treatment will reduce the mean IR, it is not known if the IR variability is also reduced.

OBJECTIVE

To compare the change in IR and its variability before and after treatment with insulin sensitization through metformin and pioglitazone, compared to that induced by weight loss with orlistat.

DESIGN

Randomized, open labelled parallel study.

SETTING

Endocrinology outpatient clinic at a referral centre.

PATIENTS

Thirty obese PCOS patients [BMI 36.0 +/- 1.2 kg/m(2) (mean +/- SEM)] participated in the study.

INTERVENTION

The change in biological variability (BV) was assessed by measuring IR (homeostasis model assessment method) at 4-day intervals on 10 consecutive occasions before and 12 weeks after randomization to metformin, pioglitazone or orlistat.

OUTCOME MEASURED

The primary end point of the study was a change in BV of IR.

RESULTS

Treatment with pioglitazone, orlistat and metformin reduced the overall IR by 41.0 +/- 4.1%, 19.7 +/- 6.4% and 16.1 +/- 6.8% (P = 0.005, P = 0.013, P = 0.17, respectively) and IR variability by 28.5 +/- 18.0%, 41.8 +/- 11.6% and 23.7 +/- 17.0 (P = 0.20, P = 0.015 and P = 0.28, respectively). Free androgen index reduced significantly with all treatments.

CONCLUSION

Only orlistat reduced both IR and its variability significantly, though all three drugs were effective in reducing hyperandrogenism within the 12-week period of the study.

The effect of atorvastatin in patients with polycystic ovary syndrome: a randomized double-blind placebo-controlled study

CONTEXT

Polycystic ovary syndrome (PCOS) is associated with increased risk of cardiovascular morbidity, whereas statins are proven to reduce cardiovascular mortality and morbidity through lipid-lowering and perhaps through their pleiotropic effects. Statins can also reduce testosterone in vitro by inhibiting ovarian theca-interstitial cell proliferation and steroidogenesis and reducing inflammation in vivo.

OBJECTIVE

Our objective was to assess the effect of atorvastatin on inflammatory markers, insulin resistance, and biochemical hyperandrogenemia in patients with PCOS.

DESIGN AND SETTING

We conducted a randomized, double-blind, placebo-controlled study at a tertiary care setting in United Kingdom.

PATIENTS

Patients included 40 medication-naive patients with PCOS and biochemical hyperandrogenemia.

METHODS

Patients were randomized to either atorvastatin 20 mg daily or placebo.

MAIN OUTCOME MEASURES

The primary endpoint of the study was a change in the inflammatory marker high-sensitivity C-reactive protein. The secondary endpoints were a change in insulin resistance and total testosterone.

RESULTS

After 12 wk atorvastatin, there was a significant reduction (mean +/- sem) in total cholesterol (4.6 +/- 0.2 vs. 3.4 +/- 0.2 mmol/liter, P < 0.01), low-density lipoprotein cholesterol (2.9 +/- 0.2 vs. 1.8 +/- 0.2 mmol/liter, P < 0.01), triglycerides (1.34 +/- 0.08 vs. 1.08 +/- 0.13 mmol/liter, P <0.01), high-sensitivity C-reactive protein (4.9 +/- 1.4 vs. 3.4 +/- 1.1 mg/liter, P = 0.04), free androgen index (13.4 +/- 0.6 vs. 8.7 +/- 0.4, P < 0.01), testosterone (4.1 +/- 0.2 vs. 2.9 +/- 0.1 nmol/liter, P < 0.01) and insulin resistance as measured by homeostasis model assessment for insulin resistance (HOMA-IR) (3.3 +/- 0.4 vs. 2.7 +/- 0.4). There was a significant increase in SHBG (31.1 +/- 1.0 vs. 35.3 +/- 1.2 nmol/liter, P < 0.01). There was a positive correlation between the reduction in HOMA-IR in the atorvastatin group with the reduction in triglycerides and the reduction of free androgen index. There was a significant deterioration of HOMA-IR in the placebo group (3.0 +/- 0.4 vs. 3.8 +/- 0.5).

CONCLUSIONS

This study suggests that atorvastatin is effective in reducing inflammation, biochemical hyperandrogenemia, and metabolic parameters in patients with PCOS after a 12-wk period.

Metformin maintains the weight loss and metabolic benefits following rimonabant treatment in obese women with polycystic ovary syndrome (PCOS)

OBJECTIVE

Rimonabant has been shown to reduce weight, free androgen index (FAI) and insulin resistance in obese patients with polycystic ovary syndrome (PCOS) compared to metformin. Studies have shown that significant weight regain occurs following the cessation of rimonabant therapy. This study was undertaken to determine if subsequent metformin treatment after rimonabant would maintain the improvement in weight, insulin resistance and hyperandrogenaemia in PCOS.

DESIGN

An extension study for 3 months with the addition of metformin to the randomised open labelled parallel study of metformin and rimonabant in 20 patients with PCOS with a body mass index >or= 30 kg/m(2). Patients who were on 3 months of rimonabant were changed over to metformin for 3 months, whereas those on 3 months of metformin were continued on metformin for another 3 months.

MEASUREMENTS

The primary end-point was a change in weight; secondary end-points were a change in FAI and insulin resistance.

RESULTS

The mean weight loss of 6.2 kg associated with 3 months of rimonabant treatment was maintained by 3 months of metformin treatment (mean change +0.2 kg, P = 0.96). Therefore, the percentage reduction in weight remained significantly higher in the rimonabant/metformin group compared to metformin only subjects at 6 months compared to baseline (-6.0 +/- 0.1%vs. -2.8 +/- 0.1%, P = 0.04). The percentage change in testosterone and FAI from baseline to 6 months was also greater in the rimonabant/metformin group. [Testosterone (-45.0 +/- 5.0%vs. -16 +/- 2.0%, P = 0.02); FAI (-53.0 +/- 5.0%vs. -17.0 +/- 12.2%, P = 0.02)]. HOMA-IR continued to fall significantly in the rimonabant/metformin group between 0, 3 and 6 months (4.4 +/- 0.5 vs. 3.4 +/- 0.4 vs. 2.7 +/- 0.3, respectively, P < 0.01) but not at all in the metformin only group (3.4 +/- 0.7 vs. 3.4 +/- 0.8 vs. 3.7 +/- 0.8, respectively, P = 0.80). Total cholesterol and LDL reduced significantly in both groups, but improvements in triglycerides and HDL were limited to the rimonabant/metformin group.

CONCLUSIONS

In these obese patients with PCOS, metformin maintained the weight loss and enhanced the metabolic and biochemical parameters achieved by treatment with rimonabant, compared to 6 months of metformin treatment alone.