Effect of sulfonylurea dose escalation on hemoglobin A1c in Veterans Affairs patients with type 2 diabetes

Reducing the Burden of Diabetes Treatment: A Review of Low-cost Oral Hypoglycemic Medications

BACKGROUND

The vast majority of individuals diagnosed with diabetes are low/middle income and may have access to only three of the 11 oral hypoglycemic medications (OHMs) due to cost: metformin intermediate release (IR) or extended release (ER), sulfonylureas (glimepiride, glipizide, glyburide), and pioglitazone. Sulfonylureas and pioglitazone have had significant controversy related to potential adverse events, but it remains unclear whether these negative outcomes are class, drug, or dose-related.

OBJECTIVE

We conducted a narrative review of low-cost OHMs.

METHODS

We evaluated the maximum recommended (MAX) compared to the most effective (EFF) daily dose, time-to-peak change in HbA1c levels, and adverse events of low-cost oral hypoglycemic medications.

RESULTS

We found that the MAX was often greater than the EFF: metformin IR/ER (MAX: 2,550/2,000 mg, EFF: 1,500-2,000/1,500-2,000 mg), glipizide IR/ER (MAX: 40/20 mg, EFF: 20/5 mg), glyburide (MAX: 20 mg, EFF: 2.5-5.0 mg), pioglitazone (MAX: 45 mg, EFF: 45 mg). Time-to-peak change in HbA1c levels occurred at weeks 12-20 (sulfonylureas), 25-39 (metformin), and 25 (pioglitazone). Glimepiride was not associated with weight gain, hypoglycemia, or negative cardiovascular events relative to other sulfonylureas. Cardiovascular event rates did not increase with lower glyburide doses (p<0.05). Glimepiride and pioglitazone have been successfully used in renal impairment.

CONCLUSION

Metformin, glimepiride, and pioglitazone are safe and efficacious OHMs. Prescribing at the EFF rather than the MAX may avoid negative dose-related outcomes. OHMs should be evaluated as individual drugs, not generalized as a class, due to different dosing and adverse-event profiles; Glimepiride is the preferred sulfonylurea since it is not associated with the adverse events as others in its class.

Predictors of response in initial users of metformin and sulphonylurea derivatives: a systematic review

AIM

To provide an overview of factors predicting metformin and sulphonylurea treatment response.

BACKGROUND

A large variability between individuals in treatment response to metformin and sulphonylurea derivatives exists. Understanding which factors determine response to these drugs may pave the way for more individualized therapy.

METHODS

We conducted a systematic search in the MEDLINE, Cochrane and EMBASE databases, between 2003 and 2012 for articles assessing demographic and clinical prediction factors of treatment response in initial users of metformin or sulphonylurea. A literature search of articles referenced within the studies identified was also performed. Treatment response was defined as change in HbA1c level, reaching target HbA1c levels or time to treatment change. Studies were assessed on quality, sample size and type of analysis. Results were summarized by tabulating positive, null and negative associations observed for included predictors.

RESULTS

A total of 10 articles (six trial reports and four cohort studies) were obtained, including three of sufficient quality. For metformin, baseline HbA1c , older age, lower BMI and shorter disease duration were found to be predictors of better treatment response in at least three studies of sufficient quality. For sulphonylurea derivatives, baseline HbA1c and shorter duration were identified as predictors of better treatment response in at least two studies of sufficient quality. Race, smoking status, lipid levels, blood pressure, kidney function and comorbidities were not significantly associated with treatment response.

CONCLUSIONS

Several demographic and clinical factors were identified as possible predictors of response to metformin and sulphonylurea, but the number of studies with sufficient quality was small. Generally, early treatment seems important for achieving better glycaemic outcomes.

Regardless of the degree of glycaemic control, linagliptin has lower hypoglycaemia risk than all doses of glimepiride, at all time points, over the course of a 2-year trial

AIM

To evaluate the risk of documented hypoglycaemia with glimepiride versus linagliptin.

METHODS

This was an exploratory analysis of data from a 2-year, randomized, double-blind study of the dipeptidyl peptidase-4 inhibitor linagliptin 5 mg once daily (n = 764) versus the sulphonylurea glimepiride 1-4 mg once daily (n = 755) in patients with type 2 diabetes uncontrolled by metformin. Patients randomized to glimepiride started on 1 mg and after 4 weeks were allowed to be individually uptitrated stepwise to glimepiride 4 mg if a fasting plasma glucose concentration ≤6.1 mmol/l was not achieved. Investigator-reported hypoglycaemia was evaluated by dose, over time, and by the degree of glycated haemoglobin (HbA1c) reduction.

RESULTS

The percentages of patients with at least one hypoglycaemic event at the individual maximum glimepiride dose were: 1 mg, 45.0%; 2 mg, 50.8%; 3 mg, 36.1%; and 4 mg, 27.7%. The incidence of hypoglycaemia was higher with glimepiride than with linagliptin (36.1 vs. 7.5%; p < 0.0001); after performing sensitivity analyses by excluding events during dose escalation (weeks 0-16), this difference remained significant (weeks 16-104: 25.8 vs. 5.9%; p < 0.0001). Notably, the incidence of hypoglycaemia was higher with glimepiride than with linagliptin in each quartile of HbA1c change from baseline (all p < 0.0001); the incidence of hypoglycaemic episodes was not increased with greater reductions in HbA1c in either group. In all 4-week intervals across the 2-year study, the incidence of hypoglycaemia was lower with linagliptin than with glimepiride.

CONCLUSION

Linagliptin was associated with a lower risk of hypoglycaemia than glimepiride at all dose levels and time intervals, and regardless of change in HbA1c level.

Sitagliptin add-on to low dosage sulphonylureas: efficacy and safety of combination therapy on glycaemic control and insulin secretion capacity in type 2 diabetes

AIMS

To assess the efficacy and safety of combination therapy with sitagliptin and low dosage sulphonylureas on glycaemic control and insulin secretion capacity in Japanese type 2 diabetes.

METHODS

Eighty-two subjects were sequentially recruited for the 52-week, prospective, single arm study. Sitagliptin was added on to sulphonylureas (glimepride or gliclazide) with or without metformin. The primary endpoint was a change in A1C. The secondary endpoints were changes in BMI, insulin secretion capacity, blood pressure and urinary albumin excretion, unresponsive rate, and hypoglycaemia. Insulin secretion capacity was evaluated by glucagon loading test.

RESULTS

Change in A1C was -0.80% (95% CI -0.90 to -0.68) (p < 0.001). Change in BMI, systemic and diastolic blood pressure, and urinary albumin excretion were -0.38 kg/m(2) (95% CI -0.72 to -0.04) (p < 0.05), -6.7/-3.6 mmHg (95% CI -10.0 to -3.4/-4.8 to -2.4) (p < 0.001), and -43.2 mg/gCr (95% CI -65.7 to -20.8) (p < 0.001) respectively. Mild hypoglycaemia was observed in three cases. The unresponsive rate was 6.1%. Glucagon loading test showed that 0-min and 6-min CPR at baseline and 52-week were not significantly changed: 0-min CPR, 1.58 ± 0.58-1.71 ± 0.73 ng/ml; 6-min CPR, 3.48 ± 1.47-3.58 ± 1.21 ng/ml. Insulin secretion capacity, CPI and SUIT index at baseline did not predict the efficacy of the combination therapy. The final dosages of glimepiride and gliclazide were 1.44 ± 0.90 mg and 34.5 ± 15.3 mg respectively. The dosage of sitagliptin was increased from 50 mg to 69.0 ± 24.5 mg in 52-week.

CONCLUSIONS

The combination therapy with sitagliptin and low dosage sulphonylureas was safe and effective for glycaemic control. Glucagon loading test indicated that 1 year administration of sitagliptin and sulphonylureas preserved insulin secretion capacity.