Improved glycemic control with minimal systemic metformin exposure: Effects of Metformin Delayed-Release (Metformin DR) targeting the lower bowel over 16 weeks in a randomized trial in subjects with type 2 diabetes.

OBJECTIVE: Metformin use is restricted in patients with renal impairment due to potential excess systemic accumulation. This study evaluated the glycemic effects and safety of metformin delayed-release (Metformin DR), which targets metformin delivery to the ileum to leverage its gut-based mechanisms of action while minimizing systemic exposure. RESEARCH DESIGNS AND METHODS: Participants (T2DM [HbA1c 7-10.5%], eGFR ≥60 mL/min/1.73m2, not taking metformin for ≥2 months) were randomized to QD placebo (PBO); QD Metformin DR 600, 900, 1200, or 1500 mg; or to single-blind BID Metformin immediate-release (IR) 1000 mg. The primary endpoint was change in HbA1c for Metformin DR vs. PBO at 16 weeks in the modified intent-to-treat (mITT) population (≥ 1 post-baseline HbA1c while on study drug), using a mixed-effects repeated measures model. RESULTS: 571 subjects were randomized (56 years, 53% male, 80% white; BMI 32.2±5.5 kg/m2; HbA1c 8.6±0.9%; 51% metformin naive); 542 were in the mITT population. Metformin DR 1200 and 1500 mg significantly reduced HbA1c (-0.49±0.13% and -0.62±0.12%, respectively, vs. PBO -0.06±0.13%; p<0.05) and FPG (Caverage Weeks 4-16: -22.3±4.2 mg/dL and -25.1±4.1 mg/dL, respectively vs. -2.5±4.2 mg/dL p<0.05). Metformin IR elicited greater HbA1c improvement (-1.10±0.13%; p<0.01 vs. Placebo and all doses of Metformin DR) but with ~3-fold greater plasma metformin exposure. Normalizing efficacy to systemic exposure, glycemic improvements with Metformin DR were 1.5-fold (HbA1c) and 2.1-fold (FPG) greater than Metformin IR. Adverse events were primarily gastrointestinal but these were less frequent with Metformin DR (<16% incidence) vs. Metformin IR (28%), particularly nausea (1-3% vs 10%). CONCLUSION: Metformin DR exhibited greater efficacy per unit plasma exposure than Metformin IR. Future studies will evaluate the effects of Metformin DR in patients with type 2 diabetes and advanced renal disease. TRIAL REGISTRATION: Clinicaltrials.gov NCT02526524.

Metformin-associated lactic acidosis: Current perspectives on causes and risk.

Although metformin has become a drug of choice for the treatment of type 2 diabetes mellitus, some patients may not receive it owing to the risk of lactic acidosis. Metformin, along with other drugs in the biguanide class, increases plasma lactate levels in a plasma concentration-dependent manner by inhibiting mitochondrial respiration predominantly in the liver. Elevated plasma metformin concentrations (as occur in individuals with renal impairment) and a secondary event or condition that further disrupts lactate production or clearance (e.g., cirrhosis, sepsis, or hypoperfusion), are typically necessary to cause metformin-associated lactic acidosis (MALA). As these secondary events may be unpredictable and the mortality rate for MALA approaches 50%, metformin has been contraindicated in moderate and severe renal impairment since its FDA approval in patients with normal renal function or mild renal insufficiency to minimize the potential for toxic metformin levels and MALA. However, the reported incidence of lactic acidosis in clinical practice has proved to be very low (<10 cases per 100,000 patient-years). Several groups have suggested that current renal function cutoffs for metformin are too conservative, thus depriving a substantial number of type 2 diabetes patients from the potential benefit of metformin therapy. On the other hand, the success of metformin as the first-line diabetes therapy may be a direct consequence of conservative labeling, the absence of which could have led to excess patient risk and eventual withdrawal from the market, as happened with earlier biguanide therapies. An investigational delayed-release metformin currently under development could potentially provide a treatment option for patients with renal impairment pending the results of future studies. This literature-based review provides an update on the impact of renal function and other conditions on metformin plasma levels and the risk of MALA in patients with type 2 diabetes.

Synthetic exendin-4 (exenatide) significantly reduces postprandial and fasting plasma glucose in subjects with type 2 diabetes.

Despite the advent of new treatments, glucose control in the type 2 diabetes population is unsatisfactory. AC2993 (synthetic exendin-4; exenatide), a novel glucose-dependent insulinotropic agent, exhibited notable antidiabetic potential in two clinical studies in patients with type 2 diabetes. In study A, 24 subjects received sc injections of study medication (0.1 micro g/kg AC2993 or placebo) twice daily with meals for 5 d. Statistically significant reductions in mean postprandial circulating concentrations of glucose, insulin, and glucagon occurred following treatment with AC2993. In study B, 13 subjects receiving a single dose of study medication (0.05, 0.1, or 0.2 micro g/kg AC2993 or placebo) following an overnight fast had reduced fasting plasma glucose concentrations during the subsequent 8-h period. The relative glucose and insulin concentration profiles were consistent with glucose-dependent insulinotropism. AC2993 was well tolerated. Mild transient headache, nausea, and vomiting were the main adverse events. In conclusion, AC2993 acutely and markedly reduces fasting and postprandial glucose concentrations in patients with type 2 diabetes. During fasting, glucose-dependent enhancement of insulin secretion and suppression of glucagon secretion are the predominant mechanisms, and postprandially, slowing of gastric emptying is additionally operative. This robust antidiabetic effect warrants further evaluation of AC2993.

Effect on glycemic control of exenatide (synthetic exendin-4) additive to existing metformin and/or sulfonylurea treatment in patients with type 2 diabetes.

OBJECTIVE: AC2993 (synthetic exendin-4; exenatide) is a peptide that enhances glucose-dependent insulin secretion, suppresses inappropriately elevated glucagon secretion, and slows gastric emptying. AC2993 also promotes beta-cell proliferation and neogenesis in vitro and in animal models. This study examines the activity and safety of subcutaneously injected AC2993 in patients with type 2 diabetes currently treated with diet and/or oral antidiabetic agents (OAAs). RESEARCH DESIGN AND METHODS: A total of 109 patients treated with diet and a sulfonylurea and/or metformin were enrolled in a blinded study. Patients were randomly assigned to one of three subcutaneously (SC) injected regimens of AC2993 (0.08 micro g/kg) or placebo for 28 days. RESULTS: All three AC2993 regimens led to significant reductions in serum fructosamine relative to placebo (P