Cardiovascular and renal outcomes of initial combination therapy with glucose-lowering agents versus a stepwise approach in newly diagnosed or treatment-naïve type 2 diabetes: A systematic review and meta-analysis

AIM

To evaluate the efficacy and safety of the initial combination therapy versus a stepwise approach in newly diagnosed type 2 diabetes (T2D) by conducting a systematic review and meta-analysis of observational cohort studies and randomized controlled trials (RCTs).

METHODS

Studies were identified from MEDLINE, Embase, the Cochrane Library, and through search of bibliographies to January 2022. Study-specific risk ratios (RRs) and mean differences with 95% confidence intervals (CIs) were pooled. Quality of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system.

RESULTS

Eight articles including four unique RCTs (n = 5527 participants) and one observational cohort study (n = 200) that compared initial combination therapy versus stepwise therapy were included. The RR for myocardial infarction comparing initial combination therapy versus stepwise therapy was 1.21 (95% CI 0.74-2.00). Initial combination therapy reduced levels of fasting plasma glucose and glycated haemoglobin: mean differences -0.97 mmol/L (95% CI -1.41, -0.53) and -24.92 mmol/mol (95% CI -25.67, -24.27), respectively. Initial combination therapy versus stepwise therapy reduced lipid levels, blood pressure and intima media thickness, with no differences in body composition variables, neuropathy, retinopathy or adverse events. Single-study results showed that initial combination therapy reduced creatinine levels and urine albumin excretion rate. The quality of the evidence ranged from moderate to very low.

CONCLUSIONS

Except for improving cardiometabolic and glycaemic variables, a limited number of studies characterized by small sample sizes show that initial combination therapy for newly diagnosed T2D may be similar in efficacy and safety to stepwise therapy with respect to cardio-renal outcomes. There is a lack of sufficient evidence to recommend initial combination therapy with glucose-lowering agents in newly diagnosed T2D with the aim of preventing cardio-renal outcomes. Definitive RCTs are warranted.

Comparison of Safety and Efficacy of Glimepiride-Metformin and Vildagliptin- Metformin Treatment in Newly Diagnosed Type 2 Diabetic Patients

OBJECTIVE

To compare the safety and efficacy of glimepiride and vildagliptin as add-on therapy to metformin in newly diagnosed patients with type 2 diabetes mellitus (T2DM).

METHODS

This 24-week, prospective, comparative, observational study was conducted among newly diagnosed patients with T2DM. The primary endpoint was a change in fasting plasma glucose (FPG), postpradinal glucose (PPG), and HbA1c from the baseline to week 24. The key secondary endpoints were monitoring treatment-emergent adverse events such as hypoglycemia, overall gastrointestinal symptoms and weight gain, and electrocardiogram (ECG) findings.

RESULTS

A total of 100 eligible patients were divided into two groups: group A (n = 50) received vildagliptin plus metformin and group B (n = 50) received glimepiride plus metformin. The mean age of the patients was 49.98 years and 52.12 years in group A and group B, respectively. Electrocardiographic findings were within normal limits in all the patients from group A, whereas 47 patients from group B showed normal ECG findings. A significant decrease in HbA1c, fasting and post-prandial plasma glucose was observed with group A and group B from the baseline to week-24. However, at week-24, reduction in HbA1c and blood glucose parameters were comparable between the groups. Safety outcomes did not show any events of hypoglycemia with vildagliptin. Mild hypoglycemia was reported with glimepiride in five patients.

CONCLUSION

Vildagliptin-metformin appeared to be equally effective to glimepiride-metformin in reducing HbA1c level and blood glucose parameters, however, resulted in better adverse event profiles with lower risks of hypoglycemia.

[Initial combination therapy for primary open-angle glaucoma]

PURPOSE

To study the efficacy and safety of initial combination therapy in patients with primary open-angle glaucoma (POAG).

MATERIAL AND METHODS

The study included 111 patients (161 eyes) with stages II-III b-c of POAG aged 46 to 89 years (mean age 70.8±8.5 years). In the test group, therapy began with a fixed combination of prostaglandin (PG) (latanoprost) and beta-blocker (BB) (timolol). In patients of the control group, POAG therapy began with administration of the analogue of prostaglandin (latanoprost). When the target IOP was not achieved, a second drug was added to the treatment - instillations of 0.5% solution of timolol maleate 2 times a day.

RESULTS

In patients of the test group the treatment started with a combination of BB + PG, the target IOP in the 'worst' eyes was achieved in 33 cases (64%) in 1.5±0.6 visits, and in the 'best' eyes - in 17 cases (81%), in 1.2±0.4 visits. In the control group with a 'step-by-step' selection of antihypertensive therapy, the target IOP in the 'worst' eyes was achieved in 35 cases (59%), in 2.5±0.7 visits, and in the 'best' eyes - in 22 cases (76%), in 2.2±0.5 visits (p<0.05). In both study groups, there were no cases of drug withdrawal attributed to their side effects. Patients noted conjunctival hyperemia in 5% (4 eyes) and 7% (6 eyes) of cases in the test group and the control group, respectively (p>0.05). Hyperemia decreased significantly in 2 weeks of latanoprost administration or fixed combination and did not cause withdrawal.

CONCLUSION

Initial combination therapy is possible in patients with newly diagnosed POAG in some clinical situations, namely in stages II-III POAG with high IOP, unavailability of regular observation of patients for various social and economic reasons, absence of somatic and local contraindications to individual components of the combined treatment, etc.

Apparent subadditivity of the efficacy of initial combination treatments for type 2 diabetes is largely explained by the impact of baseline HbA1c on efficacy

AIM

To explain the subadditive efficacy typically observed with initial combination treatments for type 2 diabetes.

METHODS

Individual subject data from 1186 patients with type 2 diabetes [mean glycated haemoglobin (HbA1c) = 8.8%] treated with metformin, canagliflozin or canagliflozin + metformin were used. The baseline HbA1c versus ΔHbA1c relationships for monotherapy arms were determined using analysis of covariance and then used to predict efficacy in the combination arms by modelling how applying one treatment lowers the 'effective baseline HbA1c' for a second treatment. The model was further tested using data from several published combination studies.

RESULTS

The mean ΔHbA1c levels were -1.25, -1.33, -1.37, -1.77 and -1.81% with metformin, canagliflozin 100 mg, canagliflozin 300 mg, canagliflozin 100 mg/metformin and canagliflozin 300 mg/metformin, respectively. Using the monotherapy results, the predicted efficacy for the canagliflozin/metformin arms was within 10% of the observed values using the new model, whereas assuming simple additivity overpredicted efficacy in the combination arms by nearly 50%. For 10 other published initial combination studies, predictions from the new model [mean (standard error) predicted ΔHbA1c = 1.67% (0.14)] were much more consistent with observed values [ΔHbA1c = 1.72% (0.12)] than predictions based on assuming additivity [predicted ΔHbA1c = 2.19% (0.21)].

CONCLUSIONS

The less-than-additive efficacy commonly seen with initial combination treatments for type 2 diabetes can be largely explained by the impact of baseline HbA1c on the efficacy of individual treatments. Novel formulas have been developed for predicting the efficacy of combination treatments based on the efficacy of individual treatments and the baseline HbA1c of the target patients.

Safety and efficacy of initial combination of linagliptin and metformin in patients with type 2 diabetes: A subgroup analysis of Indian patients from a randomized, double-blind, placebo-controlled study

CONTEXT AND OBJECTIVES

The number of people with diabetes is increasing exponentially in India. Owing to a unique "Asian Indian Phenotype," Indians develop diabetes a decade earlier and have an earlier onset of complications than Western populations. Therefore, it is essential to evaluate more effective treatment strategies at an earlier stage of disease progression, such as initial combination therapy, in Indian patients. In this study, we evaluated the efficacy and safety of initial combination therapy with linagliptin plus metformin in comparison to linagliptin or metformin monotherapy in Indian patients with type 2 diabetes mellitus.

METHODS

This is a subgroup analysis of Indian patients who participated in a Phase III, 24-week, double-blind, placebo-controlled, trial. Overall, 249 Indian patients were randomized to one of six treatment arms (Two free combination therapy arms: Linagliptin 2.5 mg twice daily [bid] + either low [500 mg, n = 36] or high [1000 mg, n = 44] dose metformin bid and four monotherapy arms: Linagliptin 5 mg once daily [qd, n = 40], metformin 500 mg [n = 49] or 1000 mg bid [n = 45], or placebo [n = 23]).

RESULTS

The placebo-corrected mean change in glycated hemoglobin from baseline (8.9%) to week 24 was -1.83% for linagliptin + metformin 1000 mg bid; -1.46% for linagliptin + metformin 500 mg bid; -1.30% for metformin 1000 mg bid; -1.00% for metformin 500 mg bid; and -0.77% for linagliptin 5 mg qd. None of the patients in the combination therapy arms had hypoglycemia, whereas there was one event in the metformin 1000 mg bid arm. Rates of adverse event were similar across various treatments.

CONCLUSIONS

In this subgroup analysis of Indian patients, initial combination therapy with linagliptin + metformin was more efficacious in improving glycemic control than the monotherapy arms, with a comparable tolerability profile. The results were comparable to the overall population.