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C-peptide profiles in young diabetics
K D Nihalani1, P K Varthakavi, K L Patel
1Department of Endocrinology, TN Medical College, Bombay.
Insights
This study on young diabetics shows that insulin sensitivity is crucial, alongside insulin secretion, for understanding diabetes presentation. C-peptide levels reveal varying insulin reserves across different diabetes types.
Area of Science:
- Endocrinology
- Metabolic Disorders
- Diabetes Mellitus Research
Background:
- Assessing C-peptide (CP) secretion is vital for understanding beta-cell function in diabetes.
- Diabetes diagnosed before age 30 presents diverse clinical and physiological profiles.
- Distinguishing between insulin-dependent (IDDM), non-insulin-dependent (NIDDM), and insulin-requiring diabetes (IRDM) is key.
Purpose of the Study:
- To evaluate the C-peptide (CP) secretory response to a glucose load in young patients with diabetes.
- To correlate CP secretory status with clinical classifications of diabetes (IDDM, NIDDM, IRDM).
- To investigate the role of insulin sensitivity and hormonal factors (GH, cortisol) in diabetes presentation.
Main Methods:
- Studied 56 patients diagnosed with diabetes before age 30.
- Classified patients into IDDM (18), NIDDM (19), and IRDM (19) groups.
- Measured basal and post-glucose load C-peptide levels, along with Growth Hormone (GH) and cortisol levels.
Main Results:
- IDDM patients showed significantly lower basal and stimulated CP levels compared to controls.
- NIDDM and IRDM patients were stratified into groups with low or preserved CP reserve.
- Elevated GH and cortisol levels were observed in IDDM and IRDM patients lacking insulin reserve.
Conclusions:
- Insulin sensitivity is as critical as insulin secretory status in determining diabetes presentation in the young.
- C-peptide response patterns help differentiate diabetes subtypes and predict disease characteristics.
- Hormonal dysregulation (GH, cortisol) is associated with specific diabetes phenotypes lacking insulin reserve.
Abstract:
Fifty-six patients who had been diagnosed diabetic prior to the age of 30 were evaluated to determine the C-peptide (CP) secretory response to a glucose load. These individuals were classified clinically as having insulin dependent (IDDM = 18); non-insulin dependent (NIDDM = 19) and insulin requiring diabetes (IRDM = 19). Insulin dependent diabetics had lower basal CP levels (0.44 +/- (SE) 0.1 ng/ml) which were not stimulated by hyperglycaemia (0.55 +/- 0.13 ng/ml) as compared to controls (basal CP = 1.6 +/- 0.2 and peak 6.2 +/- 0.8 ng/ml). Non-insulin dependent diabetics and insulin requiring diabetics could be divided broadly into two groups - one, a set of patients with low basal CP levels (NIDDM = 0.63 +/- 0.09 ng/ml) (IRDM = 0.38 +/- 0.08 ng/ml) and a blunted response to a glucose load (peak response NIDDM = 0.83 +/- 0.05 ng/ml, IRDM = 0.59 +/- 0.12 ng/ml) and a second group who had CP reserve evident in both fasting (NIDDM = 1.6 +/- 0.2 ng/ml; IRDM = 2.1 +/- 0.6) and post-glucose levels (Peak Response NIDDM = 4.6 +/- 0.4 ng/ml; IRDM = 3.0 +/- 0.6 ng/ml). Growth Hormone (GH) and cortisol levels were found to be high in patients with IDDM and IRDM with no insulin reserve and these did not suppress during the oral Glucose Tolerance Test. NIDDM patients with no insulin reserve had normal GH and high cortisol levels. It is emphasized from this study that insulin sensitivity is as important as the insulin secretory status in determining the presenting features of diabetes mellitus in the young.