Targeting intensive versus conventional glycaemic control for type 1 diabetes mellitus: a systematic review with meta-analyses and trial sequential analyses of randomised clinical trials.

OBJECTIVE: To assess the benefits and harms of targeting intensive versus conventional glycaemic control in patients with type 1 diabetes mellitus. DESIGN: A systematic review with meta-analyses and trial sequential analyses of randomised clinical trials. DATA SOURCES: The Cochrane Library, MEDLINE, EMBASE, Science Citation Index Expanded and LILACS to January 2013. STUDY SELECTION: Randomised clinical trials that prespecified different targets of glycaemic control in participants at any age with type 1 diabetes mellitus were included. DATA EXTRACTION: Two authors independently assessed studies for inclusion and extracted data. RESULTS: 18 randomised clinical trials included 2254 participants with type 1 diabetes mellitus. All trials had high risk of bias. There was no statistically significant effect of targeting intensive glycaemic control on all-cause mortality (risk ratio 1.16, 95% CI 0.65 to 2.08) or cardiovascular mortality (0.49, 0.19 to 1.24). Targeting intensive glycaemic control reduced the relative risks for the composite macrovascular outcome (0.63, 0.41 to 0.96; p=0.03), and nephropathy (0.37, 0.27 to 0.50; p<0.00001. The effect estimates of retinopathy, ketoacidosis and retinal photocoagulation were not consistently statistically significant between random and fixed effects models. The risk of severe hypoglycaemia was significantly increased with intensive glycaemic targets (1.40, 1.01 to 1.94). Trial sequential analyses showed that the amount of data needed to demonstrate a relative risk reduction of 10% were, in general, inadequate. CONCLUSIONS: There was no significant effect towards improved all-cause mortality when targeting intensive glycaemic control compared with conventional glycaemic control. However, there may be beneficial effects of targeting intensive glycaemic control on the composite macrovascular outcome and on nephropathy, and detrimental effects on severe hypoglycaemia. Notably, the data for retinopathy and ketoacidosis were inconsistent. There was a severe lack of reporting on patient relevant outcomes, and all trials had poor bias control.

Effect of adjunct metformin treatment in patients with type-1 diabetes and persistent inadequate glycaemic control. A randomized study.

BACKGROUND: Despite intensive insulin treatment, many patients with type-1 diabetes (T1DM) have longstanding inadequate glycaemic control. Metformin is an oral hypoglycaemic agent that improves insulin action in patients with type-2 diabetes. We investigated the effect of a one-year treatment with metformin versus placebo in patients with T1DM and persistent poor glycaemic control. METHODOLOGY/PRINCIPAL FINDINGS: One hundred patients with T1DM, preserved hypoglycaemic awareness and HaemoglobinA(1c) (HbA(1c)) > or = 8.5% during the year before enrolment entered a one-month run-in on placebo treatment. Thereafter, patients were randomized (baseline) to treatment with either metformin (1 g twice daily) or placebo for 12 months (double-masked). Patients continued ongoing insulin therapy and their usual outpatient clinical care. The primary outcome measure was change in HbA(1c) after one year of treatment. At enrolment, mean (standard deviation) HbA(1c) was 9.48% (0.99) for the metformin group (n = 49) and 9.60% (0.86) for the placebo group (n = 51). Mean (95% confidence interval) baseline-adjusted differences after 12 months with metformin (n = 48) versus placebo (n = 50) were: HbA(1c), 0.13% (-0.19; 0.44), p = 0.422; Total daily insulin dose, -5.7 U/day (-8.6; -2.9), p<0.001; body weight, -1.74 kg (-3.32; -0.17), p = 0.030. Minor and overall major hypoglycaemia was not significantly different between treatments. Treatments were well tolerated. CONCLUSIONS/SIGNIFICANCE: In patients with poorly controlled T1DM, adjunct metformin therapy did not provide any improvement of glycaemic control after one year. Nevertheless, adjunct metformin treatment was associated with sustained reductions of insulin dose and body weight. Further investigations into the potential cardiovascular-protective effects of metformin therapy in patients with T1DM are warranted. TRIAL REGISTRATION: ClinicalTrials.gov NCT00118937.