Body-Mass Index and Fasting Insulin Levels in Adult Diabetes

BODY-MASS INDEX AND FASTING INSULIN LEVELS IN ADULT DIABETES

VD Maheshwari, Kunal Kothari

Department of Medicine, SMS Medical College and Hospital, Jaipur 302004

High insulin levels with peripheral insulin resistance is well known in obese maturity onset diabetes patients. In India, a large number of diabetics (22-30%) are lean and the insulin metabolism in these patients is not known.1

We studied 60 recently diagnosed diabetic patients who were classified into three groups of 20 each according to body mass index (BMI): lean BMI <20 kg/m2; normal weight BMI 20-25; and obese BMI >25). Patients with acute complications of diabetes, renal failure, insulin-dependent diabetics and pregnant women were excluded. Fasting blood glucose and insulin levels were determined. A fasting insulin resistance index (FIRI) was calculated by a previously validated formula2 (FIRI= fasting blood glucose in mmol/l x fasting insulin in uU/ml) /25. The subjects were well matched for age, gender distribution, duration of diabetes and fasting glucose levels (Table).

There was a significant positive correlation of BMI with fasting insulin levels (r=0.32, p=0.012) and FIRI (r=0.34, p=0.008). In lean diabetics the fasting insulin levels were significantly lower (14.5+8.7 uU/ml) than in normal weight diabetics (56.7+20.7) or obese diabetics (86.6+139.0). FIRI was the most in obese diabetics (29.1+43.8) as compared to the other two groups (p<0.05). Insulin resistance is the least in lean diabetics. This group has low fasting insulin levels also.

Conventionally all diabetics are advised to reduce calorie intake which may decrease weight. However, in lean diabetics loss of weight is associated with a three-fold increase in mortality as shown by a longitudinal multinational study.3 Weight loss in this group exaggerates insulinopenia which is already present in this group and weight gain in order to improve insulin secretion may be proposed in lean diabetics.

Table: Clinical and Biochemical Parameters in Study Subjects

	Lean (n=20)	Normal weight (n=20)	Overweight (n=20)
Age (years)	56.9+7.8	54.5+8.7	58.1+9.1
Males (%)	75.0	70.0	45.0
BMI (kg/m2)	18.1+0.9	23.3+0.9	28.7+1.7
Diabetes Duration Year)	6.9+6.1	6.0+5.1	6.0+5.1
Fasting glucose (mg/dl)	174.2+53	128.3+40	141.7+40
Fasting insulin (uU/ml)	14.5+8.7	56.7+20.7	86.6+139.0
FIRI	6.3+4.3	17.3+6.1	29.1+43.8

Our study shows that obese diabetics have a large variation in insulin levels as suggested by large standard deviation in fasting insulin levels and FIRI (Table). This indicates that obese diabetics are a heterogeneous group with insulinopenia on one hand and insulin resistance on the other. Therapeutic approach in this group should be guided by fasting insulin levels.

REFERENCES

1.	Samal KC, Das S, Agarwal BN, Panda NC, Tripathy BB. Nutritional status and profile of NIDDM of recent onset. J Diab Assoc India 1988; 28:99-101
2.	Duncan MH, Singh BM, Wise PH, Carter G. A simple measure of insulin resistance. Lancet 1995; 346:120-121
3.	Chaturvedi N, Fuller JH. Mortality risk by body weight change in people with NIDDM. The WHO multinational study of vascular disease in diabetes. Diabetes Care 1995; 18:766-774

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EDITOR IN CHIEF

Dr. Rajeev Gupta
(MD PhD FACC)

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Dr. Soneil Guptha
(MD FACC FESC)

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