Comparison of additional metformin or NPH insulin to mealtime insulin lispro therapy with mealtime human insulin therapy in secondary OAD failure

Aim: It has been found that non-fasting plasma glucose is a better marker of diabetic control than fasting plasma glucose in type 2 diabetes. The main aim of treatment of type 2 diabetic patients is to control plasma glucose and HbA(1c) levels. In this study, we aimed to assess the effects of three different insulin regimens (group I: lispro insulin + NPH insulin, group II: lispro insulin + metformin and group III: regular insulin + NPH insulin) on overall glycaemic control and metabolic parameters in type 2 diabetic patients with secondary oral anti-diabetic drug failure. Methods: Sixty type 2 diabetic patients with secondary OAD failure were randomly allocated into three different treatment groups equally. There were no significant differences between groups concerning age, body mass index, diabetes duration, HbA(1c) and serum lipid levels at the beginning of the study. During the 6-month treatment period, blood glucose levels were determined 10 times during 24 h at pre-meal, post-prandial 1 and 2 h and at bedtime. Results: Group I was found to be the most effective treatment regimen in controlling HbA(1c) levels (group I vs. group II, p = 0.013; group I vs. group III, p = 0.001; group II vs. group III, p > 0.05). When the comparison was made in each group, change in HbA(1c) was statistically significant for all groups (-3.18%, p = 0.001; -2.02%, p = 0.043 and -2.66%, p = 0.008 respectively). Group I was found to be more effective in controlling fasting and post-prandial plasma glucose levels measured at all times during the day when compared with group II and group III. In group II triglyceride levels were found to be significantly reduced, whereas other groups had no effect on lipids. No serious hypoglycaemic episodes were observed in any of the cases, whereas in group I hypoglycaemic episode rates were increased (chi(2) = 8.843, p = 0.012). Conclusions: Lispro insulin plus NPH insulin regimen is more effective in controlling both pre- and post-prandial glucose levels and HbA(1c) when compared to regular insulin plus NPH insulin combination. Mealtime lispro insulin plus metformin combination therapy should also be seriously considered as an effective and alternative treatment regimen. It is worthy of attention that insulin lispro plus metformin lowered triglyceride levels.