The contribution of metformin to glycaemic control in patients with Type 2 diabetes mellitus receiving combination therapy with insulin

Composite cardiovascular risk and BMI affected comparative profiles of BIAsp 30 + metformin vs BIAsp 30 monotherapy: a MERIT post-hoc analysis

We assessed whether comparative efficacy and safety of biphasic insulin aspart 30 (BIAsp 30) plus metformin versus BIAsp 30 monotherapy differed for patients with type 2 diabetes mellitus (T2DM) inadequately controlled with oral antidiabetic drugs with different cardiovascular risk scores and different body mass indexes (BMI) by performing a post hoc analysis of the randomized controlled MERIT study. In the MERIT study, eligible patients were randomized 1:1 to receive BIAsp 30 plus metformin or BIAsp 30 for 16 weeks. Patients in the 2 treatment groups were classified into "low" and "high" risk subgroups based on their GloboRisk scores and into "BMI ≤ 26 kg/m²"and "BMI > 26 kg/m²" subgroups. Primary efficacy endpoint was between-treatments comparison of HbA1c changes from baseline for these 2 sets of subgroups. Between-treatments comparisons of secondary efficacy and safety endpoints were also performed. We found that BIAsp 30 plus metformin led to significantly higher percentage of high-risk patients achieving HbA1c target < 7% than BIAsp 30 monotherapy, with an overall comparable safety profile for high-risk patients. Meanwhile, for patients with BMI ≤ 26 kg/m², compared with BIAsp 30 monotherapy, BIAsp 30 plus metformin led to significantly higher percentages of patients achieving HbA1c target (47.83% vs 28.17%, P = 0.0165) and composite target of HbA1c < 7% without hypoglycemia or weight gain (20.29% vs 6.85%, P = 0.0187) and have a slightly better safety profile. In conclusion, for T2DM patients at high CV risk or with BMI ≤ 26 kg/m², BIAsp 30 plus metformin was preferable to BIAsp 30 monotherapy.

Glycaemic control in native Kuwaiti Arab patients with type 2 diabetes

AIMS

To evaluate the influence of age at diabetes diagnosis, diabetes duration, BMI, comorbidity with hypertension and medication regimen on glycaemic control in native Kuwaiti Arab patients with T2D.

METHODS

This cross-sectional study considered 7657 patients from Kuwait Diabetes Registry and analysed data from their laboratory and hospital records.

RESULTS

HbA1c and prevalence of hypertension increased significantly with diabetes duration. Duration of diabetes (β=0.034; P<0.001) and age at diagnosis (β=-0.03; P<0.001) were independently associated with HbA1c. Inadequate glycaemic control was more likely in patients diagnosed at <60 than in those ≥60 years of age (OR:1.80, 95%-CI:1.39-2.31). Increasing duration of diabetes witnessed decrease in metformin prescription and increase in sulfonylureas prescription; proportion of patients treated with insulin increased from 5.6% to 44.4% in 9 years of diagnosis. Patients with 9-years duration of diabetes or with combination therapy of insulin-metformin-sulfonylureas differed in mean BMI for adequate or inadequate glycaemic control (29.5 versus 31.2kg/m²; P<0.001 and 29.8 versus 33.2; P<0.01, respectively).

CONCLUSIONS

Only 25.6% of the T2D patients in this ethnic cohort exhibited adequate glycaemic control. The delineated relationship of inadequate glycaemic control with diabetes duration, onset age, obesity and hypertension prevalence has a bearing on diabetes management programs for Arabs.

A justification for less restrictive guidelines on the use of metformin in stable chronic renal failure

AIM

The aim was to justify less restrictive use of metformin in stable chronic renal failure, because a literature review reveals metformin is associated with a significantly lower incidence of cardiovascular events and mortality compared with other hypoglycaemic agents, and metformin-associated lactic acidosis is rare and causation uncertain. Studies on intentional metformin overdose and metformin bioavailability, renal clearance and plasma metformin in renal impairment provide evidence in support of a less restrictive use of metformin.

METHODS

In metformin overdose (n = 22), lactic acidosis was not inevitable with a plasma metformin > 40 mg/l (therapeutic level c. 1 mg/l): Severe lactic acidosis (pH ≤ 7.21, plasma lactate ≥ 11 mmol/l, n = 8) did not occur unless plasma metformin was > 40 mg/l. Plasma lactate was a more consistent predictor of pH than plasma metformin, with plasma lactate ≤ 4.7 being associated with a pH ≥ 7.34. A likely 'safe' plasma lactate is < 3.5 mmol/l and plasma metformin < 10 mg/l.

RESULTS

Plasma metformin can be predicted from estimated glomerular filtration rate and metformin dose. Reported plasma metformin in renal failure was always less than predicted plasma metformin. Predicted plasma metformin (mg/l), with an estimated glomerular filtration rate of 30 ml/min and metformin 2000 mg/day was 6.8; an estimated glomerular filtration rate of 20 ml/min and metformin 1500 mg/day was 5.1; an estimated glomerular filtration rate of 10 ml/min and metformin 500 mg/day was 4.4.

CONCLUSION

Metformin accumulates in renal failure and, although accumulation does not always lead to lactic acidosis, dose modification to achieve a predicted plasma metformin < 10 mg/l is suggested. As plasma metformin is not routinely available, plasma lactate should be useful in monitoring the use of metformin in renal failure.

Insulin therapy in type 2 diabetes: what is the evidence?

AIM

To systematically review the literature regarding insulin use in patients with type 2 diabetes mellitus

METHODS

A Medline and Embase search was performed to identify randomized controlled trials (RCT) published in English between 1 January 2000 and 1 April 2008, involving insulin therapy in adults with type 2 diabetes mellitus. The RCTs must comprise at least glycaemic control (glycosylated haemoglobin (HbA1c), postprandial plasma glucose and /or fasting blood glucose (FBG)) and hypoglycaemic events as outcome measurements.

RESULTS

The Pubmed search resulted in 943 hits; the Embase search gave 692 hits. A total of 116 RCTs were selected by title or abstract. Eventually 78 trials met the inclusion criteria. The studies were very diverse and of different quality. They comprised all possible insulin regimens with and without combination with oral medication. Continuing metformin and/or sulphonylurea after start of therapy with basal long-acting insulin results in better glycaemic control with less insulin requirements, less weight gain and less hypoglycaemic events. Long-acting insulin analogues in combination with oral medication are associated with similar glycaemic control but fewer hypoglycaemic episodes compared with NPH insulin. Most of the trials demonstrated better glycaemic control with premix insulin therapy than with a long-acting insulin once daily, but premix insulin causes more hypoglycaemic episodes. Analogue premix provides similar HbA1c, but lower postprandial glucose levels compared with human premix, without increase in hypoglycaemic events or weight gain. Drawing conclusions from the limited number of studies concerning basal-bolus regimen seems not possible. Some studies showed that rapid-acting insulin analogues frequently result in a better HbA1c or postprandial glucose without increase of hypoglycaemia than regular human insulin.

CONCLUSION

A once-daily basal insulin regimen added to oral medication is an ideal starting point. All next steps, from one to two or even more injections per day should be taken very carefully and in thorough deliberation with the patient, who has to comply with such a regimen for many years.

Glycaemic responsiveness to long-term insulin plus sulphonylurea therapy as assessed by sulphonylurea withdrawal

AIMS

To assess the effect of sulphonylurea (SU) in patients with Type 2 diabetes undergoing long-term combination therapy with insulin, by withdrawal of SU, and to identify clinically useful markers of long-term response.

METHODS

We studied 25 patients, aged 59-83 years, mean glycated haemoglobin (HbA(1c)) 7.0 +/- 0.6%, who had been treated with SU for 16 years (7-24 years) in combination with insulin for 10 years (6-15 years). After basal measurements, SU was withdrawn. Fasting plasma glucose (FPG) and C-peptide were then monitored every 2-3 days during the following 2 weeks. If FPG increased > 40% or P-glucose exceeded 20 mmol/l, SU was restarted. If neither criterion was met, a clinical follow-up visit with measurement of HbA(1c) was scheduled within 8 weeks.

RESULTS

Twenty patients were restarted on SU because of worsening glycaemic control, eight within the first 4 weeks and the remaining 12 at the follow-up visit as their HbA(1c) had increased by 1.1% (range 0.4-2.0%). All these patients were defined as 'SU responders'. The increase in FPG during the initial 2 weeks correlated positively with duration of diabetes (P < 0.01) and duration of SU treatment (P < 0.001). The 'SU responders' had higher levels of basal fasting C-peptide (0.84 +/- 0.44 vs. 0.41 +/- 0.15 nmol/l, P < 0.05), but the variation was wide and none of the measured variables identified 'SU responders'.

CONCLUSIONS

In 80% of this group of patients, glycaemic control deteriorated after SU withdrawal despite long duration of SU treatment.

Biphasic insulin aspart 30 plus metformin: an effective combination in type 2 diabetes

AIM

This study compared glycaemic control achieved with biphasic insulin aspart 30 (BIAsp 30) monotherapy, BIAsp 30 plus metformin and glibenclamide plus metformin in patients with type 2 diabetes not adequately controlled with metformin.

METHODS

In this multinational, open-labelled, parallel group, 16-week trial, 341 patients (patients not adequately controlled with metformin for at least 1 month) with type 2 diabetes were studied. Patients were randomized to receive BIAsp 30, twice daily (n = 107 exposed to treatment), or BIAsp 30, twice daily, plus metformin (n = 108) or glibenclamide plus metformin (n = 114). The primary endpoint was HbA(1c) at end of trial; adverse events, hypoglycaemia episodes, blood lipids and weight were also monitored.

RESULTS

In the total population (HbA(1c) 7.5-13.0% at screening), end-of-trial HbA(1c) levels were lower in patients receiving BIAsp 30 plus metformin compared with those receiving BIAsp 30 only [mean treatment difference (+/-s.e.m), 0.39 +/- 0.15%, p = 0.007]. In a subpopulation (HbA(1c) > or = 9.0% at baseline, n = 193), patients receiving BIAsp 30 plus metformin had significantly lower HbA(1c) levels at the end of the trial compared with those receiving glibenclamide plus metformin (treatment difference, 0.46 +/- 0.21%, p = 0.027). Mean body weight (+/-s.d) at the end of the trial was significantly lower in patients receiving glibenclamide plus metformin compared with those receiving BIAsp 30 only (84.3 +/- 13.3 kg vs. 88.9 +/- 16.9 kg, p < 0.001). No major hypoglycaemic episodes were recorded during the trial, and incidence rates for minor and symptoms-only hypoglycaemia were low and similar between treatment groups (0.03-0.04 events/patient/week).

CONCLUSION

BIAsp 30 added to metformin could be an appropriate therapeutic option for achieving good glycaemic control, compared with the addition of a second oral agent, particularly where HbA(1c) > or = 9%.

Comparison of additional metformin or NPH insulin to mealtime insulin lispro therapy with mealtime human insulin therapy in secondary OAD failure

AIM

It has been found that non-fasting plasma glucose is a better marker of diabetic control than fasting plasma glucose in type 2 diabetes. The main aim of treatment of type 2 diabetic patients is to control plasma glucose and HbA1c levels. In this study, we aimed to assess the effects of three different insulin regimens (group I: lispro insulin + NPH insulin, group II: lispro insulin + metformin and group III: regular insulin + NPH insulin) on overall glycaemic control and metabolic parameters in type 2 diabetic patients with secondary oral anti-diabetic drug failure.

METHODS

Sixty type 2 diabetic patients with secondary OAD failure were randomly allocated into three different treatment groups equally. There were no significant differences between groups concerning age, body mass index, diabetes duration, HbA1c and serum lipid levels at the beginning of the study. During the 6-month treatment period, blood glucose levels were determined 10 times during 24 h at pre-meal, post-prandial 1 and 2 h and at bedtime.

RESULTS

Group I was found to be the most effective treatment regimen in controlling HbA1c levels (group I vs. group II, p = 0.013; group I vs. group III, p = 0.001; group II vs. group III, p > 0.05). When the comparison was made in each group, change in HbA1c was statistically significant for all groups (-3.18%, p = 0.001; -2.02%, p = 0.043 and -2.66%, p = 0.008 respectively). Group I was found to be more effective in controlling fasting and post-prandial plasma glucose levels measured at all times during the day when compared with group II and group III. In group II triglyceride levels were found to be significantly reduced, whereas other groups had no effect on lipids. No serious hypoglycaemic episodes were observed in any of the cases, whereas in group I hypoglycaemic episode rates were increased (chi2 = 8.843, p = 0.012).

CONCLUSIONS

Lispro insulin plus NPH insulin regimen is more effective in controlling both pre- and post-prandial glucose levels and HbA1c when compared to regular insulin plus NPH insulin combination. Mealtime lispro insulin plus metformin combination therapy should also be seriously considered as an effective and alternative treatment regimen. It is worthy of attention that insulin lispro plus metformin lowered triglyceride levels.