***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: The stimulation of insulin vs. inhibition of glucagon secretion in relation to the antidiabetic action of glucagon-like peptide-1 ( GLP-1 ) is not established . Here , the influence of a 4-wk increase in circulating GLP-1 by inhibition of dipeptidyl peptidase-4 ( DPP-4 ) on 24-h glucose and insulin and glucagon responses to breakfast was studied in subjects with dietary controlled diabetes [ age : 65 + /- 8 yr ( SD ) , body mass index : 27.3 + /- 3.3 kg/m(2 ) , fasting plasma glucose : 9.0 + /- 1.3 mmol/liter ] . Compared with placebo ( n = 19 ) , a specific DPP-4 inhibitor [ ( 1-[[(3-hydroxy-1-adamantyl ) amino ] acetyl]-2-cyano-(S)-pyrrolidine ) ( LAF237 ) ; 100 mg daily , n = 18 ] reduced fasting glucose by 0.70 mmol/liter ( P = 0.037 ) , 4-h pr and ial glucose excursion by 1.45 mmol/liter ( P < 0.001 ) , and mean 24-h glucose by 0.93 mmol/liter ( P < 0.001 ) . Baseline and postpr and ial active GLP-1 were increased by LAF237 . The glucagon response to breakfast was reduced by LAF237 ( glucagon levels at 60 min were 88 + /- 8 pg/ml before treatment vs. 77 + /- 5 pg/ml after ; P = 0.001 ) . In contrast , the overall insulin levels were not altered . The 4-wk reduction in glucagon correlated with the reduction in 2-h glucose ( r = 0.61 ; P = 0.008 ) . No such association was observed for insulin . Thus , improved metabolic control by DPP-4 inhibition in type 2 diabetes is seen in association with reduced glucagon levels and , despite the lower glycemia , unaltered insulin levels Introduction Saxagliptin , sitagliptin , and vildagliptin are dipeptidyl peptidase-4 ( DPP-4 ) inhibitors widely approved for use in patients with type 2 diabetes . Using a crossover design , the present study compared trough levels of DPP-4 inhibition provided by these agents in a single cohort of patients with type 2 diabetes . Methods This was a r and omized , placebo-controlled , open-label , five-period crossover study . Eligible patients were 18–65 years of age , either treatment-naïve or off prior antihyperglycemic agent therapy for at least 6 or 12 weeks ( depending on the prior therapy ) , and had glycated hemoglobin ( HbA1C ) ≥6.5 % and ≤10.0 % . In separate study periods , patients received 5 mg saxagliptin q.d . ( saxa-5 ) , 100 mg sitagliptin q.d . ( sita-100 ) , 50 mg vildagliptin q.d . ( vilda-50-q.d . ) , 50 mg vildagliptin b.i.d . ( vilda-50-b.i.d . ) , or placebo for 5 days . The primary endpoint was trough % DPP-4 inhibition , derived by comparing DPP-4 activity 24 h after the Day-5 morning dose with predose activity in the same period and analyzed using a linear mixed-effects model with fixed-effects terms for treatment and period . Results Mean ( range ) baseline HbA1C was 7.4 % ( 6.4–9.0 % ; N = 22 ) . Least-squares ( LS ) mean trough % DPP-4 inhibition was 73.5 % , 91.7 % , 28.9 % , 90.6 % , and 3.5 % after saxa-5 , sita-100 , vilda-50-q.d . , vilda-50-b.i.d . , and placebo , respectively . In patients treated with sita-100 , the LS-mean difference in trough % DPP-4 inhibition was 18.2 % greater than with saxa-5 ( p < 0.001 ) , 62.9 % greater than with vilda-50-q.d . ( p < 0.001 ) , 1.1 % greater than with vilda-50-b.i.d . ( p = 0.128 ) , and 87.8 % greater than with placebo ( p < 0.001 ) . Mean % DPP-4 inhibition was nearly maximal at 12 h postdose regardless of active treatment . Thus , these between-group comparisons at trough primarily reflected differences in duration of action . Adverse events reported during the study were transient and mild or moderate in intensity . Conclusion Once daily treatment with sitagliptin provided trough DPP-4 inhibition significantly greater than saxagliptin or vildagliptin administered once daily , and similar to that provided by vildagliptin administered twice daily Aim : To investigate the safety , tolerability , pharmacokinetics and pharmacodynamics of linagliptin in patients with type 2 diabetes mellitus ( T2DM ) 
    Output:
    
Our study indicated that DPP-4 inhibitors show greater efficacy in Japanese patients than in non-Japanese patients , which may be an important consideration in the global development strategy of new diabetic medications