BACKGROUNDFew studies have given suggestions on appropriate initiation insulin dosage when combined with oral antidiabetic drugs (OADs). This research was to investigate appropriate initiation insulin doses for insulin-naive type 2 diabetes patients with different combinations and the relationship between insulin dosage and relevant factors.

METHODSThis was a randomized, open-label, treat to target study. The target was 20% decrease of both fasting plasma glucose (FPG) and 2 hours post-breakfast blood glucose (P2hBG). One hundred and forty-seven insulin-naive Chinese patients recruited were randomly assigned to 3 groups: group A, patients received insulin monotherapy; group B, received insulin plus metformin (0.5 g, tid) and group C, received insulin plus metformin (0.5 g, tid) and pioglitazone (15 mg, qd). Insulin doses were initiated with a dose of 0.3 U×kg(-1)×d(-1) and titrated according to FPG and P2hBG till reached the targets.

RESULTSBoth the time of getting 20% reduction of FPG and P2hBG showed significant differences among the three groups. The time was shortest in Group C. The insulin doses needed to achieve glucose reduction of 20% in three treatment groups were (0.40 ± 0.04) U×kg(-1)×d(-1) for Group A, (0.37 ± 0.04) U×kg(-1)×d(-1) for Group B, and (0.35 ± 0.03) U×kg(-1)×d(-1) for Group C, respectively. Multiple linear stepwise regression analysis showed that insulin doses correlated with body weight, FPG, diabetes duration, age and history of sulfonylurea treatment. The standardized regression coefficients were 0.871, 0.322, 0.089, 0.067 and 0.063 (with all P < 0.05).

CONCLUSIONSTo achieve blood glucose's reduction of 20% within safety context, initial insulin doses were recommended as the following: 0.40 U×kg(-1)×d(-1) for insulin mono-therapy, 0.37 U×kg(-1)×d(-1) for insulin plus metformin treatment, and 0.35 U×kg(-1)×d(-1) for insulin plus metformin and pioglitazone treatment in Chinese type 2 diabetes outpatients. Body weight is found the most closely related factor to the insulin dosage.