Why HDL Is Low But Other Parameters Are In Normal Range?

My friend is 45 years old and he has been diagnosed diabetic (FBS – 278mg/dl & PPBS – 350mg/dl) and slightly high lipid profile while doing annual medical checkup. Last year his blood sugar was board line (FBS - 112mg/dl and PPBS – 132mg/dl). Then doctor put him on medicines: Glycomet GP2 (1 tab morning 15min before breakfast & 1 tab evening 15min before dinner), Istavel 100mg (1 tab morning 15min before breakfast) & Lipicard 160mg (1 tab after breakfast) with diet and exercise. After one month the test result was FBS-98mg/dl, PPBS-115mg/dl, HbA1c-10.7% & Urine report-Normal After two months the test result was FBS-77mg/dl & PPBS-84mg/dl After three months the test result was FBS-86mg/dl, PPBS-81mg/dl, HbA1c-6.4% & Urine report-Normal CHOL TOTAL-143 mg/dl, TGL-92mg/dl, HDL-34mg/dl, LDL-104 mg/dl, VLDL-5 mg/dl, CHOL HDL Ratio-4.21 Doctor, kindly advice whether he can discontinue Istavel 100mg? Why HDL is till low but other parameters are in normal range?