Nor Azwany, Yaacob
An interventive study of the effects of therapeutic lifestyle changes and
simvastatin on the insulin sensitivity status of non obese hyperlipidaemic
subjects.
Universiti Sains Malaysia.
(Submitted)
Abstract
Obesity, hyperlipidaemia and insulin resistance are known to have relationship thus
making it important to look into the insulin resistance in a group of non-obese
hyperlipidaemic subjects. This study was designed to determine insulin sensitivity and
secretory status of non-obese normoglycaemic subjects, and to find out the relationship
between hyperlipidaemia and insulin sensitivity in a non-obese population. In addition,
the second phase of this study looked at the effects of lipid lowering interventions on
insulin sensitivity in h)'perlipidaemic subjects. A cross sectional study involving 246 nonobese
(BMI<25 kg/m2
), waist circumference male<l 02cm, female <88cm) and nondiabetic
subjects aged between 30-60 years was carried out. The subjects underwent
OGTT, LFT and RFT to exclude type 2 diabetes, IGT, IFG, renal and liver diseases.
Fasting plasma glucose, fasting insulin and lipid profile were measured. Insulin
sensitivity and secretory status were computed using the homeostasis model assessment
(HOMA) software to obtain HOMA%S, HOMA%B and HOMA-IR. The subjects were
divided into two groups according to their lipid status and their insulin sensitivity was
compared between the two groups. Two groups of 28 non-obese hyperlipidaemic and 28
normolipidaernic subjects participated in the intervention study. They underwent 3
months of therapeutic lifestyle changes (TLC) regimen after which they were again
divided into TLC and Simvastatin groups and for the subsequent three months went
through either TLC only or TLC plus Simvastatin. Finally their insulin sensitivity and
lipid status were assessed again. The hyperlipidaemic subjects showed substantially
lower insulin sensitivity and higher insulin resistance in comparison to normolipidaemic
subjects. The adjusted mean of HOMA%S of hyperlipidaernic and normolipidaemic
subjects were 80 and 155 (p<O.OOOl) respectively. Insulin secretory status as expressed
by the mean of HOMA%B was 178 and 116 for hyperlipidaernic and normolipidaemic
subjects respectively. It indicates that the B cells of hyperlipidaemic subjects have to
secrete more insulin to overcome the lowered insulin sensitivity. Intervention by both
TLC and Sirnvastatin showed significant reduction of insulin resistance (62.3%
improvement of HOMA-IR in TLC group and 51.44% in Sirnvastatin and TLC group)
and improvement of insulin sensitivity (142% improvement of HOMA%S in TLC group
and 122% in Sirnvastatin and TLC group) in hyperlipidaernic subjects with reduction of
lipid levels. It can thus be concluded that, insulin sensitivity of otherwise healthy nonobese
hyperlipidaemic subjects is lower than norrnolipidaemic subjects. Therapeutic life
style changes is able to improve the insulin sensitivity in this group of subjects .
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