This study was designed to measure insulin secretory and sensitivity status of non-obese hyperlipidaemic and normolipidaemic Malay subjects and to find out their relationship with different blood lipids and to determine the effectiveness of TLC and lipid lowering drug Simvastatin on insulin sensitivity of these subjects. In the first step of research a cross sectional study was done on 246 subjects aged between 30-60 years. Insulin sensitivity and secretory status were computed using the homeostasis model assessment (HOMA) software to obtain HOMA%S, HOMA%B and HOMA-IR. In the second step intervention by TLC and Simvastatin was done in hyperlipidaemic subjects. The hyperlipidaemic subjects showed substantially lower insulin sensitivity and higher insulin resistance in comparison to normolipidaemic subjects. HOMA%B was high in hyperlipidaemicsubjects. Which indicated that the pancreatic B cells of these subjects have to secrete more insulin to overcome the relative ...