in the past decades it had been asserted that glucose intolerance in niddm patients can arise from several causes . numerous accumulated evidences support the notion that insulin resistance and decrease of insulin secretory capacity are the major causes of glucose intolerance in niddm . although the majority of niddm patients has normal or increased serum insulin concentration and 24-hour urinary c - peptide excretion , many of them require insulin therapy in practice without any improvement by diet therapy and oral hypoglycemic agents . many factors are taken into consideration to use insulin such as degree of blood glucose elevation , history of actual ketosis , relative body weight , complications , duration of disease , success or failure of the previous treatment modalities . however , there has been no useful criteria for the insulin therapy before one begin to start diet therapy and oral hypoglycemic agents . reported that the patients with peak value of less than 60u / ml for serum insulin concentration or less than 6.0 ng / ml for serum c - peptide concentration during oral glucose tolerance test did not normalize the blood glucose concentration after weight reduction and required an additional oral hypoglycemic agent or insulin . rendell et al . advocated that patients with fasting and glucose stimulated plasma c - peptide values similar to those in normal subjects were diet - controlable diabetes . to determine whether postprandial 2hr serum c - peptide level is useful indicator for insulin treatment in niddm , we performed the retrospective analysis of several clinical characteristics according to the classification by postprandial 2hr serum insulin , c - peptide level and 24-hour urinary c - peptide excretion . subjects were 67 patients ( 37 male and 30 female ) with niddm admitted from february , 1981 to may , 1984 , in kyung hee university hospital . blood glucose was measured by glucose oxidase method , hba1c by column method and plasma insulin and c - peptide were measured by radioimmunoassay ( daiichi radioisotope laboratories ) . all patients were classified in three ways by serum insulin , c - peptide , 24-hr urine c - peptides and reclassified into 3 groups ( table 2 ) on the basis of normal values which we reported previously ( table 1 ) . group 1 of each classification had values above 1 s.d of mean and group 3 had values below 1 s.d of mean . in each group classified according to the postprandial 2-hr serum insulin level ( table 3 ) . the higher response group of insulin ( group i1 ) was more obese than the lower response group ( group i3 ) . their weight indices were 1.13  0.14 , 0.98  0.12 respectively . fasting blood sugar and hba , ( p<0.005 ) the incidence of diabetic complications was lower in group i1 , ( 13% ) than in group i3 ( 43% ) . in the classification according to the level of postprandial 2-hr serum c - peptide ( table 4 ) . there were similar results to the classification according to insulin level but more significant discrimination between two groups , ( group c1 , c3 ) . in the classification the higher response group ( group u1 ) was more obese than the lower response group ( group u3 ) , ( p<0.005 ) . their weight indices were 1.13 0.15 , 0.97  0.12 respectively . fasting blood sugar was lower in group u1 , ( 188.5  85.6 ) than in group u3 ( 272.9  81.5 mg / dl ) . the incidence of diabetic complications was lower in group u1 ( 9% ) than in group u3 ( 62% ) . when these results were compared with the above results by the classification according to the level of postprandial 2-hr serum c - peptide , the incidence of diabetic complications had no difference but fasting blood sugar and hba1c presented more significant difference in the classification according to postprandial 2-hr serum c - peptide level . in the classification according to the level of postpradial 2-hr serum insulin ( table 6 ) . diet - controllable diabetic patients ( pp2hr blood sugar ; less than 200 mg / dl ) were 6 ( 33% ) in group i , but zero in group i3 . remarkably , one patient in group i1 , was receiving insulin on admission but was able to control by diet , only on discharge . the patients receiving insulin on discharge were 9 ( 50% ) in group i1 , 17 ( 100% ) in group i3 . in the classification according to the level of postprandial 2-hr serum c - peptide , ( table 7 ) . diet - controllable diabetics were 12 ( 55% ) in group c1 but zero in group c3 . the diabetics receiving insulin on discharge were 5 ( 22% ) in group c1 , 29 ( 97% ) in group c3 . in the classification according to the level of 24-hr urine c - peptide ( table 8) . diet - controllable diabetics were 4 ( 29% ) in group u1 , but none in group u3 . the diabetics receiving insulin on discharge were 8 ( 57% ) in group u1 , 19 ( 95% ) in group u3 . at the point , diet - controllable diabetics may be present higher response ( such as group i1 , c1 , u1 , ) than diabetics requiring additional treatment one would think that the classification according to the level of postprandial 2-hr serum c - peptide is a more sensitive index for insulin treatment than other classifications . in each group classified according to the postprandial 2-hr serum insulin level ( table 3 ) . the higher response group of insulin ( group i1 ) was more obese than the lower response group ( group i3 ) . their weight indices were 1.13  0.14 , 0.98  0.12 respectively . fasting blood sugar and hba , ( p<0.005 ) the incidence of diabetic complications was lower in group i1 , ( 13% ) than in group i3 ( 43% ) . in the classification according to the level of postprandial 2-hr serum c - peptide ( table 4 ) . there were similar results to the classification according to insulin level but more significant discrimination between two groups , ( group c1 , c3 ) . in the classification the higher response group ( group u1 ) was more obese than the lower response group ( group u3 ) , ( p<0.005 ) . their weight indices were 1.13 0.15 , 0.97  0.12 respectively . fasting blood sugar was lower in group u1 , ( 188.5  85.6 ) than in group u3 ( 272.9  81.5 mg / dl ) . the incidence of diabetic complications was lower in group u1 ( 9% ) than in group u3 ( 62% ) . when these results were compared with the above results by the classification according to the level of postprandial 2-hr serum c - peptide , the incidence of diabetic complications had no difference but fasting blood sugar and hba1c presented more significant difference in the classification according to postprandial 2-hr serum c - peptide level . in the classification according to the level of postpradial 2-hr serum insulin ( table 6 ) . diet - controllable diabetic patients ( pp2hr blood sugar ; less than 200 mg / dl ) were 6 ( 33% ) in group i , but zero in group i3 . remarkably , one patient in group i1 , was receiving insulin on admission but was able to control by diet , only on discharge . the patients receiving insulin on discharge were 9 ( 50% ) in group i1 , 17 ( 100% ) in group i3 . in the classification according to the level of postprandial 2-hr serum c - peptide , ( table 7 ) . diet - controllable diabetics were 12 ( 55% ) in group c1 but zero in group c3 . the diabetics receiving insulin on discharge were 5 ( 22% ) in group c1 , 29 ( 97% ) in group c3 . in the classification according to the level of 24-hr urine c - peptide ( table 8) . diet - controllable diabetics were 4 ( 29% ) in group u1 , but none in group u3 . the diabetics receiving insulin on discharge were 8 ( 57% ) in group u1 , 19 ( 95% ) in group u3 . at the point , diet - controllable diabetics may be present higher response ( such as group i1 , c1 , u1 , ) than diabetics requiring additional treatment one would think that the classification according to the level of postprandial 2-hr serum c - peptide is a more sensitive index for insulin treatment than other classifications . diabetes consisted of juvenile - onset diabetes and adult - onset diabetes in past years , but several inconsistencies were indicated in this classification . at present , diabetes are classified into three groups ; iddm , niddm , secondary diabetes according to the propose by national diabetes data group in 1973 . iddm is almost always characterized by a nearly total absence of endogenous insulin secretion from pancreatic -cells and caused by an inflammatory process , so called insulitis . therefore , all insulin dependent diabetics require insulin to sustain life because of proneness to ketosis and severe hyperglycemia . in contrast , niddm has no defects in insulin secretion from pancreatic -cell and may results from a specific receptor or post - receptor defect namely , insulin resistance in target tissues of insulin . since yallow et al . reported the methods employed in the immunoassay of endogenous insulin in 1960 , these facts become more clear . therefore , the principle of treatment is a removal of the causes of insulin resistance . for the treatment of diabetes , it has no disagreement that insulin therapy is mandatory for the treatment of iddm . because the pathogenic mechanism of niddm is insulin resistance and level of insulin in patients with niddm are normal or increased a few modalities for treatment are applied to patients with niddm , diet only , diet and oral hypoglycemic agent , diet and insulin . and yet , diet therapy remains the most important method for treatment of niddm because weight reduction by diet improves insulin resistance and restores the sensitity of tissues to insulin . in practice , a physician has to use insulin in the patient whose blood sugar has not been controlled by diet therapy and oral hypoglycemic agents . therefore , there occurs a question how we predict one to need the insulin thereapy before starting diet therapy and oral hypoglycemic agent . published that patients with peak values of less than 60 u / ml for insulin or less than 6.0 ng / ml for c - peptide induced during oral glucose tolerance testing did not normalize the blood sugar concentration after weight reduction and required additional oral hypoglycemic agent or insulin . rendell et al . advocated that patients with fasting and glucose - stimulated plasma c - peptide values similar to those in normal subjects were diet - controllable diabetes and others needed oral hypoglycemic agents or insulin . in another study , they reported that insulin secretory capacity was measured by c - peptide responsle during a standard oral glucose tolerance test in patient who achieved normalization of plasma glucose level only by dietary regimen . summed c - peptide levels of the diabetics controlled by diet therapy was higher than for normal weight , nondiabetic volunteers . asserted that the response of immunoassayable c - peptide to an intravenous glibenclamide - glucose load in diabetics was useful index in order to predict which patients would be manageable with glibenclamide tablets and which would require insulin . madsbad et al . contended that serum c - peptide concentration measured 6 minutes after an i.v . injection of 1 mg glucagon seemed to be of value in the out patient clinic to discriminate non - insulin dependent from insulin - dependent patients . the above reporters performed prospective study but we did a retrospective study and discovered similar results with them . we measured the post - pradial 2-hr response of insulin or c - peptide because diabetics present the peak response about 2-hr after meal , which is different from peak response about 3060 min in normal subjects . in addition , we measured the 24-hr urine c - peptide in order to determine a more precise index for insulin treatment . in the classification according to the level of postprandial 2-hr serum c - peptide and 24-hr urine c - peptide , ( table 7 , 8) diet - controllable diabetics were 12 ( 55% ) , 4 ( 29% ) in higher group ( c1 , u1 , ) respectively and insulin needed diabetics were 29 ( 97% ) , 19 ( 95% ) in lower group ( c3 , u3 ) respectively . 12 ( 55% ) in the higher response group ( c1 ) was controlled by diet . especially , one who was diagnosed as cva was controlled by insulin transiently after admission and then , by diet after discharge . it was believed that cva , one acute stress could aggravate glucose intolerance transietly in this patient . nondiet - controllable diabetics in group c1 were 10 ( 45% ) , 5 of them required insulin therapy . by previous reports two had no specific diseases and required daily 30 u , 40 u of insulin on admission and reduced to 20 u , 12 u 3 months , 5 months later respectively . rest one was a patient with cva and required 60 u of insulin on admission . but we also expect that the dose of insulin will be decreased in near future . therefore , we could get the result that the classification according to postprandial 2-hr serum c - peptide is a more sensitive indicator for the requirement of insulin therapy than that according to 24-hr urine c - peptide . the reason why the 24-hr urinary c - peptide was less sensitive may arise from the fact that postprandial 2-hr serum c - peptide reflects secretory response of insulin newly synthesized from pancreatic -cell after mixed meal , but 24-hr urine c - peptide reflects the total insulin secretory capacity of pancreatic -cell throughout meal , emotional stress , and other during all the day . published the results of their study as follows : in glucose tolerance test ( 100 g ) characterized by measurement of induced insulin secretion , diabetic complication of retinopathy , sensory neuropathy and renal disease developed only in the group of patients that the induced serum insulin peak fell below 60u / ml and who showed greater than this were not associated with development of these complications . they suggested that a critical amount of insulin secretory reserve could distinguish the qualitatively distinct clinical syndrome , true diabetes from the syndrome of pure resistance to insulin . most diabetics needed insulin therapy had more frequent diabetic complications and lower level of postprandial 2-hr serum insulin , c - peptide and 24-hr urine c - peptide . in conclusion , to predict the diabetics need insulin therapy , the duration of diabetes mellitus , presence of diabetic complications , degree of sugar elevation , and failure of previous treatment modalities are important factors but the level of postprandial 2-hr serum insulin and c - peptide , 24-hr urine c - peptide are more important factors . among them , the classification according to postprandial 2-hr c - peptide level is a most sensitive guide for insulin treatment .
to determine the usefulness of postpradial-2hr serum c - peptide as a guide for insulin treatment in niddm , the 67 niddm patients admitted in kyung hee university hospital from nov . 
 1981 to may 1984 were classified according to postprandial 2-hr insulin , c - peptide levels and 24-hr urine c - peptide levels.the patients were divided into 3 groups according to the level of insulin or c - peptide in normal persons reported previously.9)in 22 patients with postprandial 2-hr values of more than 5.8 ng / ml for c - peptide , 12 patients ( 55% ) were diet controllable and only 5 patients ( 22% ) required insulin treatment . on the other hand , in the classification according to postprandial 2-hr insulin or 24-hr urine c - peptide levels , higher response groups should be controlled by diet alone , but 9 of 18 patients ( 50% ) for insulin , 8 of 14 patients ( 57% ) for 24-hr urine c - peptide required insulin treatment.the classification according to postprandial 2hr c - peptide levels was a more sensitive guide for insulin treatment than that with postprandial 2hr insulin level or 24hr urine c - peptide level .