Objective: Predictive factors for successful insulin therapy in type 2 diabetic patıents with poor glycemic control despite using maximum dose of oral antidiabetic therapy were investigated.

Method: One hundred forty five patients (age 57.00±11.05 yrs, body mass index (BMI) 28.8±5.4 kg/m2, diabetes duration 11.6±7.8 yrs) with type 2 diabetes according to WHO criteria using insulin therapy for at least 6 months because of poor glycemic control with maximum dose of oral antidiabetic drugs for a minimum of 6 months were included in the study. Fasting blood sugar, basal c-peptide level, HbA1c, blood presure, BMI, and serum lipids were evaluated before and after insulin therapy.

Results: Fasting blood sugar and HbA1c levels decreased significantly after insulin treatment (p<0.001, for both). The overall increase in body weight was about 4.3 kg (p<0.001). When we evaluated the patients at the end of the second year of insulin treatment, there were a strong correlation between the age of onset of diabetes, insulin treatment beginning age, diabetes duration, and insulin requirement (r = 0.19, p<0.01, r = -0.24, p<0.05, r = -0.21, p<0.01). We also found significant correlation between diabetes duration, insulin treatment beginning age (r = 0.90, p<0.01), and c-peptide levels (r = -0.37, p<0.01). Patients were divided into two groups according to the age of onset of diabetes (group 1 ?40 yrs, group 2 >40 yrs). In the first group, HbA1c level and insulin requirement were found to be high, although c-peptide levels were low. Insulin treatment beginning age was found to be low compared to the second group. Patients with diabetes duration longer than 10 years had poor metabolic control (HbA1c % 8.12±0.95, p<0.05) and low c-peptide levels (2.92±1.41 ng/ml, p<0.05).

Conclusion: At the end of the second year of the insulin treatment in type 2 diabetics, patients had weight gain about 4.3 kg despite good metabolic control values. Earlier age of onset of diabetes (especially ?40 yrs), longer diabetes duration and high BMI were the independent predictors of the successful insulin treatment.