Introduction

Lipid accumulation product index is a simple index for estimating lipid over accumulation among adults described by Kahn⁷⁷ which is computed from waist circumference (WC, cm and triglycerides (TGs, mmol/l): (WC-65) ×TG (men) and (WC-58) ×TG (women).

This index was defined to describe the extent to which an individual had travelled the route of both increasing waist circumference and increasing TG level. The LAP had been noted performed better than BMI in identifying US adults at cardiovascular risk.⁷⁷ Lipid accumulation product index has also been noted to correlate positively with HOMA-IR index in studies carried out in healthy individuals and in women with polycystic ovarian syndrome in China and Brazil respectively.^78,79 The LAP index had been shown to have high efficiency in predicting metabolic syndrome in Argentinian and Taiwanese adult population.^16,80 Similar finding was also noted in a study carried out by Ejike et al¹⁰ in Nigerian male geriatric population.The LAP index score of 34.5 has adequate sensitivity and specificity for detecting a state of IR.⁷⁸

46 2.7 CAUSES OF INSULIN RESISTANCE

Specific conditions and agents that may cause insulin resistance include the following:

- Increased production of insulin antagonists. A number of disorders are associated with this effect, such as Cushing syndrome, acromegaly, and stress states, such as trauma, surgery, diabetes ketoacidosis, severe infection, uraemia, and liver cirrhosis.

- Medications: Agents associated with insulin resistance syndrome include glucocorticoids, cyclosporine, niacin and protease inhibitors.

- Increasing age - Obesity - Pregnancy

- Infection or severe illness - Stress

- Physical inactivity

2.8 TREATMENT OF INSULIN RESISTANCE

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The main emphasis in the treatment of IR is to manage the underlying risk factors (obesity, physical inactivity) through lifestyle changes. Associated clinical conditions should also be treated if present.

2.8.1 MANAGEMENT OF UNDERLYING RISK FACTORS a). Obesity

Weight reduction deserves first priority in individuals with abdominal obesity. Both weight reduction and maintenance of a lower weight can be achieved by a combination of reduced caloric intake and increased physical activity. Bariatric surgery may be used for severe obesity.⁸¹

b). Physical Inactivity

Increasing physical activity assists in weight reduction which reduces overall atherosclerotic cardiovascular disease (ASCVD) risks. Current recommendations are ≥30 minutes of moderate-intensity exercise, such as brisk walking, on most days of the week.

c). Atherogenic and Diabetogenic Diets

Diets low in saturated fats, trans fats, cholesterol, sodium, and simple sugars should be encouraged.⁸² Ample intakes of fruits, vegetables, and whole grains; fish intake should also be encouraged.

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2.8.2 MANAGEMENT OF ASSOCIATED CLINICAL CONDITIONS

Beyond lifestyle therapies directed toward underlying risk factors, attention must be given to associated clinical conditions.

a) Dyslipidaemia

This condition consists of abnormal levels of triglycerides and apo B, small LDL particles, and low HDL-C. Low density lipoprotein cholesterol lowering drugs like statins should first be instituted followed by a triglyceride-lowering drug.²⁶ For this reason; combining a fibrate or nicotinic acid with LDL-C-lowering treatment is an option.⁸³

b) Elevated Blood Pressure

Mild elevations of blood pressure often can be effectively controlled with lifestyle therapies:

weight control, increased physical activity, alcohol moderation, sodium reduction, and increased consumption of fresh fruits and vegetables and low-fat dairy products, in accord with the Dietary Approaches to Stop Hypertension (DASH) diet. If hypertension cannot be adequately controlled by lifestyle therapies, antihypertensive drugs should be instituted.⁸⁴

c) Elevated Fasting Glucose

In patients with IFG or IGT, weight reduction, increased physical activity, or both will delay (or prevent) the onset of T2DM. In addition, biguanides, thiazolidinedione and alpha glucosidase inhibitors will lower risk for T2DM in people with IFG or IGT.

2.9 CHAPTER TWO CONCLUSION

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Insulin resistance has been noted to play a major role in the pathogenesis of T2DM and group of diseases that make up MS. The gold standard method to measure IR, the HEC technique is unsuitable for clinical based studies because it is invasive, expensive, time-consuming and technically demanding. Other reference methods of measuring IR all have their advantages and limitations especially as regards to cost and ease of application in routine clinical practise. These limitations had led to the need for search for simple, cheap and readily available surrogate markers of insulin resistance for easy assessment of IR in routine clinical practise.

Simple surrogate markers of IR markers like serum bilirubin, visceral adiposity index, lipid accumulation product, waist to height ratio, waist circumference and triglyceride to HDL-cholesterol ratio and have been proposed for routine clinical practice. This will help in the easy detection of IR in low resource settings and in clinical studies and hence lead to initiation of early treatment for IR and hence reduced morbidity and mortality from associated clinical conditions.

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