Next, the role of INS VNTR in obesity and its related traits is questionable, since recent large-scale studies failed to replicate the earlier positive associations.
We reproduced the association of diabetes-associated variants with proinsulin/insulin ratios, and also examined the association of a TCF7L2 haplotype with obesity in the Framingham Heart Study (FHS).
The promoter SNP INS CA-11156 was the most consistently associated SNP and was associated significantly with all measures of obesity, except the visceral:subcutaneous ratio (P-values 0.009-0.03).
Multipoint variance component linkage analysis was used to identify genetic location(s) influencing IRS-related traits of obesity (BMI and WC), dyslipidemia (LTG and HDLC), and insulin levels (LSPI); the analysis identified a broad chromosomal region spanning approximately 24 cM.
In multiple regression analysis, fasting levels of proinsulin and proinsulin/insulin ratios were positively associated both with the 2-hour glucose level (as a continuous variable) and with obesity, whereas a negative association was found with birth weight.
For our patients, clinical features are most helpful in differentiating NIDDM-Y from IDDM and include ethnic background, age and gender at diagnosis (approximately 80% of First Nation patients from northern Manitoba are adolescent females), presence of obesity and acanthosis nigricans, lack of symptoms or weight loss, and strong family history of NIDDM.
Furthermore, the association of higher insulin and proinsulin levels with the likelihood of a patient having or not having CAD disappears after adjustment for BMI, suggesting that insulin and proinsulin are not independent risk markers but are primarily dependent on obesity.
Restoration of growth hormone (GH) response to GH-releasing hormone in elderly and obese subjects by acute pharmacological reduction of plasma free fatty acids.